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My take on this -

Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(A) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.
- Read the highlighted part. Run on problem.

(B) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.
- Read the highlighted part. Run on problem.

(C) Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.
- Who is using the accelerator mass spectrometry? an advanced technique?

(D) Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.
- use of "them" is dangling. Even if it refers to scholars, it is wrong.

(E) The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.
- IMO CORRECT
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AVRonaldo
Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(A) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(B) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(C) Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(D) Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(E) The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

Hi ,

The basic concept tested here is meaning. Most of the options use the wrong modifier words to convey the intended meaning.

Option A,B and D:- Based/Basing on accelerator mass spectrometry, Scholars/them...determine... The meaning conveyed through this wording is that the scholars were based on accelerator mass spectrometry, an absurd meaning. The scholars actually used accelerator mass spectrometry to determine.... Further, in option D the pronoun 'them' is ambiguous.

Option E, 'The use' singular does not agree with the plural verb 'have'.

Only option C remains and is appropriate in using the words "using the accelerator mass spectrometry..." to convey the intended meaning. Also, the appositive phrase "an advanced technique..." is correctly placed after spectrometry to explain it. There is no other position this appositive can be placed in the given sentence without altering the construction of the sentence, altogether.
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Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

"based on" is used for the application of information. This advanced technique is using accelerator mass spectrometry so "based on" is not the right phrase. Eliminate A, B, and D.

(C) Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(E) The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos."have" does not agree with "the use," and "extinct.." should be close to Glyptodon and Holmesina
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AVRonaldo
Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(A) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(B) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(C) Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(D) Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(E) The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.


Correct option : C

A) "Based on ....." clause modifier is modifying the subject "scholars" and hence making it misplace modifier error. Thus Incorrect

B) same error as in option A. Thus Incorrect

C ) "using accelerator ...." clause modifier is properly modifying the subject "scholars". And extra information "an advanced technique that makes it ....." is a noun + noun modifier (noun = advanced technique ; noun modifier = that makes it .......) and this modifier correctly modifying "accelerator mass spectrometry". Hence it is correct option

D) " Basing them"...basing whom?...them is not clearly referring to any particular noun. Moreover, the nouns that are present in this sentence such as scholars can not be based on "accelerator mass spectrometry". Hence this sentence has clear pronoun error plus serious meaning error. Thus Incorrect.

E) Here the main subject is "the use" which is singular but the verb used here is plural (have enabled). Hence this sentence has subject verb agreement error. Thus it is incorrect.

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Shalabh09
Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.


A. Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

B. Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

C. Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

D. Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

E. The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.


Correct option : C

A) "Based on ....." clause modifier is modifying the subject "scholars" and hence making it misplace modifier error. Thus Incorrect

B) same error as in option A. Thus Incorrect

C ) "using accelerator ...." clause modifier is properly modifying the subject "scholars". And extra information "an advanced technique that makes it ....." is a noun + noun modifier (noun = advanced technique ; noun modifier = that makes it .......) and this modifier correctly modifying "accelerator mass spectrometry". Hence it is correct option

D) " Basing them"...basing whom?...them is not clearly referring to any particular noun. Moreover, the nouns that are present in this sentence such as scholars can not be based on "accelerator mass spectrometry". Hence this sentence has clear pronoun error plus serious meaning error. Thus Incorrect.

E) Here the main subject is "the use" which is singular but the verb used here is plural (have enabled). Hence this sentence has subject verb agreement error. Thus it is incorrect.

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Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.


A. Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

"That" cannot modify to "samples" before. So, it's wrong

B. Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

Lack of "those" beside "neccessary" makes sentence become vague

C. Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

Correct one, "Using accelerator.." modified by "scholars"
"sample" and "those" are compared

D. Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

Which is "them"?

E. The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

"The use of.." is singular subject, so we need singular verb
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Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

a) The sentence is starting with a verb-ed phrase. The noun that verb-ed phrase or word modifies must immediately precede it or follow it. Scholars have been able to determine something using accelerator mass spectrometry.
b) The noun+noun modifier: an advanced technique that makes…………dating modifies mass spectrometry.
c) That refers to advanced technique and thus takes a singular verb. But this is the verb for that and not advanced technique.
d) Scholars is a plural noun and thus take plural verb form ‘have been’.
e) Recovered is again a verb-ed modifier that modifies the preceding nouns Glyptodon and Holmesina.
f) Extinct large mammals similar to armadillos is a dangling modifier. The placement of this modifier is incorrect. Extinct…………..are called noun phrases and technical term for such modifiers is appositive phrases which must be placed close to the noun they modify.
Options:
Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.
Incorrect

Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.
Same verb error

Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.
Correct answer. Using accelerator mass spectrometry, scholars have been able to determine something.

Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.
The pronoun ‘them’ does not have a clear antecedent. And this choice sounds awkward. Basing them on something, scholars did something. Not a very good construction.

The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.
The use (singular subject) does not agree with plural verb (have enabled).



Important point to understand:
1) A verb-ed modifier always refers to the CLOSEST noun. For example:
Disappointed by his performance in recent exams, Jake decided to party tonight.

To check if this modifier is correct or not:
Jake is disappointed by his performance in recent exams.
If it makes sense then the placement of modifier is correct.


Therefore in this sentence, verb-ed has been changed to verb-ing.
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AVRonaldo
Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(A) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(B) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(C) Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(D) Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(E) The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(A) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

This makes it seem like the scholars were based on accelerator mass spectrometry. Plus, 'extinct...aramadillos' is referring to? OUT.

(B) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

Same as A. The verb-ed modifier is incorrect and makes it seem like the scholars were based on accelerator mass spectrometry.


(C) Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.
Verb-ing modifier correctly modifies the clause and gives us a action, and result scenario i.e. Using XXXX, scholars were able..
'Extinct... armadillos' is correct modifying Glyptodon and Holmesina.


(D) Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

Basing them on accelerator mass spectrometry? 'Them' is who? Scholars or Samples? OUT.


(E) The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.
The use have enabled -> SV disagreement. OUT!

So C is the answer.
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(A) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(B) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(C) Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(D) Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(E) The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.
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AVRonaldo
Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(A) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(B) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(C) Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(D) Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(E) The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

Solution: C

Since this sentence is underlined in its (incredibly long) entirety, you can save yourself an especially hefty chunk of time by looking for differences that jump out between the answer choices. Scanning only the ends of the answers choices reveals a split between two possible endings; the choice in the original sentence improperly situates extinct large mammals similar to armadillos, an appositive which should immediately follow Glyptodon and Holmesina. The introductory phrase is a modifier that attempts to link to scholars. The participle using makes this link legitimate, because it describes the scholars’ activity.

(A) Based on ... incorrectly modifies scholars; the comparison between samples (plural) and that (singular) is awkward; extinct large mammals is not in proper apposition to Glyptodon and Holmesina.

(B) Based on ... incorrectly modifies scholars; the sentence lacks a noun after than to stand in comparison to samples.

(C) Correct. Using accelerator mass spectrometry correctly modifies scholars; samples and those stand properly in comparison; extinct large mammals ... is in appropriate apposition to Glyptodon and Holmesina.

(D) In both of its appearances, the pronoun them lacks a clear reference.

(E) Verb agreement problem. The singular subject, use, does not agree with the plural verb have enabled.

Official explanation

Solution: C

Since this sentence is underlined in its (incredibly long) entirety, you can save yourself an especially hefty chunk of time by looking for differences that jump out between the answer choices. Scanning only the ends of the answers choices reveals a split between two possible endings; the choice in the original sentence improperly situates extinct large mammals similar to armadillos, an appositive which should immediately follow Glyptodon and Holmesina. The introductory phrase is a modifier that attempts to link to scholars. The participle using makes this link legitimate, because it describes the scholars’ activity.

(A) Based on ... incorrectly modifies scholars; the comparison between samples (plural) and that (singular) is awkward; extinct large mammals is not in proper apposition to Glyptodon and Holmesina.

(B) Based on ... incorrectly modifies scholars; the sentence lacks a noun after than to stand in comparison to samples.

(C) Correct. Using accelerator mass spectrometry correctly modifies scholars; samples and those stand properly in comparison; extinct large mammals ... is in appropriate apposition to Glyptodon and Holmesina.

(D) In both of its appearances, the pronoun them lacks a clear reference.

(E) Verb agreement problem. The singular subject, use, does not agree with the plural verb have enabled.
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(A) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than that necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.

(B) Based on accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(C) Using accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(D) Basing them on accelerator mass spectrometry, which allowed them to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, scholars have been able to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina, extinct large mammals similar to armadillos, recovered from the La Brea Tar Pits.

(E) The use of accelerator mass spectrometry, an advanced technique that makes it possible to obtain radiocarbon dates from samples much smaller than those necessary for traditional radiocarbon dating, have enabled scholars to determine impressively precise radiocarbon ages for samples of Glyptodon and Holmesina recovered from the La Brea Tar Pits, extinct large mammals similar to armadillos.
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In option B , is it right to use "Based on accelerator mass.., Scholars...", as I think that Based on is rightly modifying Scholars Or is it that "Using accelerator mass ..., Scholars.." is the right way to say when you are saying that based on a study or using a study ?

I understand that this option has other errors too and hence it can be eliminated but wanted to understand from the POV of usage of "Using" and "Based on"

GMATNinja egmat please help elaborate
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nivi2084

You're absolutely right. The initial modifier needs to work with the subject of the sentence. So if we start with "Based on," the subject needs to be the actual thing that was based on something. "Using" tells us that the scholars used the technique, so that works.
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Hello DmitryFarber GMATNinja VeritasKarishma and other experts,

Can you please confirm whether 'THAT' can be used to refer to any kind of noun (based on the context of the sentence) - singular or plural and masculine or feminine?

Option A uses 'that' to refer to 'samples' - is this incorrect?
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NischalSR
Hello DmitryFarber GMATNinja VeritasKarishma and other experts,

Can you please confirm whether 'THAT' can be used to refer to any kind of noun (based on the context of the sentence) - singular or plural and masculine or feminine?

Option A uses 'that' to refer to 'samples' - is this incorrect?
If "that" is used as a modifier -- specifically a relative pronoun, if you enjoy jargon -- it can describe a singular or plural noun. Tim can break the toy that he bought, or he can break the toys that he bought.

If "that" is used as a stand-in for a noun (known as a demonstrative pronoun for the jargon-lovers), it must refer to a singular noun. California's economy is as large as that of France. Or the economies of North America are faring better than those of Europe.

So in (A), the "that," a stand-in for "samples," is a problem. We want the plural "those," which is what we get in (C).

I hope that helps!
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NischalSR
Hello DmitryFarber GMATNinja VeritasKarishma and other experts,

Can you please confirm whether 'THAT' can be used to refer to any kind of noun (based on the context of the sentence) - singular or plural and masculine or feminine?

Option A uses 'that' to refer to 'samples' - is this incorrect?

Singular/Plural usage of 'that' is discussed in this post:
https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2017/0 ... t-on-gmat/

There is no masculine/feminine distinction.
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NischalSR

Can you please confirm whether 'THAT' can be used to refer to any kind of noun (based on the context of the sentence) - singular or plural and masculine or feminine?

Option A uses 'that' to refer to 'samples' - is this incorrect?
Our book EducationAisle Sentence Correction Nirvana discusses the various avatars of “that”. Have attached the corresponding section of the book, for your reference.
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Avatars of that.pdf [245.5 KiB]
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