On November 14th, 1971, the unmanned NASA spacecraft Mariner 9 orbited

On November 14th, 1971, the unmanned NASA spacecraft Mariner 9 orbited the planet Mars and succeeded in its mission to contribute to Martian atmospheric studies, mapping Martian surface features from the lowest possible altitude, and detect heat sources from Martian volcanoes in search of evidence of recent volcanic activity.

A) to contribute to Martian atmospheric studies, and mapping Martian surface features from the lowest possible altitude, it detected
B) to contribute to Martian atmospheric studies, while mapping the Martian surface features from the lowest possible altitude, detecting
C) to contribute to Martian atmospheric studies, map the Martian surface from the lowest possible altitude, and detect
D) contributing to Martian atmospheric studies, mapping the Martian surface from the lowest possible altitude, and detecting
E) contributing to Martian atmospheric studies, it had mapped the Martian surface from the lowest possible altitude, and detected

This is a question of parallelism.
The NASA spacecraft did 3 things.
1. contribute
2. map and
3. detect

Option C is the only one satisfying to X, Y and Z parallelism rule.

D introduces forced parallelism distorting the meaning.

E uses past perfect tense improperly.

B uses while and detecting incorrectly.

In A, there is parallelism error and the sentence in the question and sentence in option A are different whereas they should be same according to GMAT question rule.

This passage basically lists the mission objectives of the Mars bound spacecraft. So the options which are unnecessarily ending with 'ing' can easily be eliminated.

Although this question has 2 groups of 3 vs 2 answer choices, this question is still of high level and so is a good question. The group with 3 answer choices is incorect and that eases the question to answer a bit.

Rest two answer choices are, by themselves, are grammatically correct and so one needs to have concept of meaning and preferenc of meaning change over grammer to answer this question. This question clearly demonstrate the preference of meaning over just grammer rules to answer the question.

Good question. Waiting for OA.

Interesting.

I think C is right, but why is D wrong? (it does not sound good, but what is the explanation?)

C) to contribute to Martian atmospheric studies, map the Martian surface from the lowest possible altitude, and detect

D) contributing to Martian atmospheric studies, mapping the Martian surface from the lowest possible altitude, and detecting

I think A B and C are out because they suggest mission was to contribute to studies.
Had in option E looks awkward,
Hence going with D

OA can always surprise

Map and Detect seems to be the ways how the contribution is done. From available options C seems better than the rest.

Every mission has a purpose. The infinitive’s sole is purpose is to indicate such purpose; a participle is no alternative to an infinite to express the right meaning, notwithstanding the correctness of the grammar. This dumps D

A) to contribute to Martian atmospheric studies, and mapping Martian surface features from the lowest possible altitude, it detected

B) to contribute to Martian atmospheric studies, while mapping the Martian surface features from the lowest possible altitude, detecting

C) to contribute to Martian atmospheric studies, map the Martian surface from the lowest possible altitude, and detect

D) contributing to Martian atmospheric studies, mapping the Martian surface from the lowest possible altitude, and detecting

E) contributing to Martian atmospheric studies, it had mapped the Martian surface from the lowest possible altitude, and detected[/quote]

Ans : C

A) parallelism error : to contribute..., and mapping, it detected
B) Parallelism error : to contribute... while mapping.. detecting
C) Seems correct : it describe 3 tasks... to contribute... to map... and to detect...
D and E both change the meaning by using present continuous tense +ing form of verb. E uses past perfect in first part of the parallel structure and simple past in second.

Bit stumped between two choices. Not sure what the intended meaning of the sentence is.

On November 14th, 1971, the unmanned NASA spacecraft Mariner 9 orbited the planet Mars and succeeded in its mission to contribute to Martian atmospheric studies, mapping Martian surface features from the lowest possible altitude, and detect heat sources from Martian volcanoes in search of evidence of recent volcanic activity.

A) to contribute to Martian atmospheric studies, and mapping Martian surface features from the lowest possible altitude, it detected

B) to contribute to Martian atmospheric studies, while mapping the Martian surface features from the lowest possible altitude, detecting

C) to contribute to Martian atmospheric studies, map the Martian surface from the lowest possible altitude, and detect

D) contributing to Martian atmospheric studies, mapping the Martian surface from the lowest possible altitude, and detecting

E) contributing to Martian atmospheric studies, it had mapped the Martian surface from the lowest possible altitude, and detected


Well in my view, in Option D there should be a comma after the word "mission" followed by verb-ing modifiers "contributing..,mapping... and detecting..." in order to give the result of the preceding clause(Answering the question what was the result of the successful mission?).

Since a comma is missing in option D i eliminate it.

Hence the answer is C.....waiting for the OA

On November 14th, 1971, the unmanned NASA spacecraft Mariner 9 orbited the planet Mars and succeeded in its mission to contribute to Martian atmospheric studies, mapping Martian surface features from the lowest possible altitude, and detect heat sources from Martian volcanoes in search of evidence of recent volcanic activity.

A) to contribute to Martian atmospheric studies, and mapping Martian surface features from the lowest possible altitude, it detected=> not ||el

B) to contribute to Martian atmospheric studies, while mapping the Martian surface features from the lowest possible altitude, detecting=> not ||el

C) to contribute to Martian atmospheric studies, map the Martian surface from the lowest possible altitude, and detect=> perfect

D) contributing to Martian atmospheric studies, mapping the Martian surface from the lowest possible altitude, and detecting=>changes the meaning

E) contributing to Martian atmospheric studies, it had mapped the Martian surface from the lowest possible altitude, and detecting=>changes the meaning

Label : Green -> ||el objects
This is a 3-2 split; D & E may misguide 'coz the -ing phrase is seemingly ||el; but does not sound logical.

PS. I do not read the option A at all; so did not realize that it is actually different form the underlined portion; don't think that should ever happen in GMAT though

Rgds.

difference between C and D , is more of grammar than of logic
rule : noun+comma+ verb-ing >> the verbing modifier modifies the preceding clause ,ie tha action of the clause
rule : noun + verbing (our case) >> the verbing modifier modififs the preciding noun

here contributing , mapping and detecting are all modifying the noun "mission"

now ask yourselves , is the "mission" itself contributing??? mapping?? NO
a mission has a purpose
anda purpose is always denoted by "to +verb" .. for eg : i will go to school to educate my self : "to educate" purpose of my going to school.

please remember the above rules

Hi Experts,

A) to contribute to Martian atmospheric studies, and mapping Martian surface features from the lowest possible altitude, it detected

In the above option the "comma + and" construction means that the sentence following it is an Independent sentence right? The "IT" after the comma in the end refers to the subject in the first half of the main sentence (spacecraft) righT?? If these points are correct, can someone explain why option A is incorrect?

TIA

Hello,
I need some help here.
This is how I see the original sentence:
On November 14th, 1971, the unmanned NASA spacecraft Mariner 9 orbited the planet Mars and succeeded in its mission to contribute to Martian atmospheric studies, and [mapping Martian surface features from the lowest possible altitude, it detected heat sources from Martian volcanoes in search of evidence of recent volcanic activity].

"mapping...altitude" acts as modifier of "it detected heat sources from Martian volcanoes in search of evidence of recent volcanic activity". Since it mapped the surface feature from lowest possible altitude, it was able to detect heat signatures. This reasoning also seems plausible.
", and" acts as a correct separator of two independent clauses.

Though other choices are grammatically correct, they change the meaning of the original sentence.
So i would prefer A to other choices.

Could anyone explain the error in my reasoning?

Regards,
Ankit

Anandanwar

I see your point here, but there are some reasons to avoid A. First, notice that before "mapping" we have ", and." If "mapping" were meant to be a modifier, the comma should appear directly before it: "and, mapping . . . altitude, it detected." This would be some pretty clunky writing, but it might work. However, the comma BEFORE "and" indicates that this is not the intent.

Second, if we had that adverbial modifier in front of the "it detected" clause, it creates a conflict with the second modifier. "Mapping . . . , it detected heat sources in search of evidence." Now we seem to be saying that it only detected heat sources in search of evidence because it mapped from a low altitude. But surely the "in search of evidence" part came first and was not dependent on the mapping part. In other words, the spacecraft was in search of evidence, and that's why it looked at volcanoes.

Third, the overall structure this interpretation creates is not clear or parallel: "The craft ordered and succeeded and, mapping, it detected." We'd need a rewrite (perhaps with a semicolon) to make this work.

On a separate note, you don't want to use "changes the meaning" as a criterion for eliminating choices. This relies on the assumption that A conveys the correct meaning, and you can't rely on that! Rather, it's necessary to use all 5 choices to get a sense of the intended meaning, and then choose an answer that correctly conveys that meaning.