Glaciers that are seated in deep submarine basins are

Question

Glaciers that are seated in deep submarine  basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, have been rapidly retreating  in the last decades.

(A)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, have been rapidly retreating
(B)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, have been rapidly retreated
(C)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, and are rapidly retreating
(D)basins, vulnerable to small changes in ocean temperature, occurred over the 20th century and have been rapidly retreating
(E)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, and have been rapidly retreating

blueseas · Accepted Answer

IMO E.

IN THE GIVEN SENTENCE THE PART " such as those that occurred over the 20th century"==>this is a modifier.hence we can remove this.
sentence becomes:
Glaciers that are seated in deep submarine basins  are vulnerable  to small changes in ocean temperature  have been  rapidly retreating  in the last decades.==> the error in this sentence is that two verbs are there and one subject
subject: glaciers....verbs: are vulnerable...and have been......=>whenever two verbs are there and both verbs belongs to same single subject then we have to connect those two verbs using a conjunction depending on the meaning of sentence.
more over in the last part of non underlined section we have: IN THE LAST DECADE===> THIS is a marker for present perfect tense...so use of HAVE (AS THE SUBJECT IS PLURAL).
NOW basing this two error (conjunction is required and use of have is required)we can eliminate A,B,AND C.

now left with D and E
(D)basins, vulnerable to small changes in ocean temperature, occurred over the 20th century and have been rapidly retreating==> HERE WE DONT HAVE THE VERB IN MAIN CLAUSE... and here.OCCURED ==> ACTING AS PAST PARTICIPLE.HENCE THIS ONE IS A FRAGMENT.
(E)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, and have been rapidly retreating(CORRECT)

KUDOS if it helped.

AndrewN · Answer

Hello,  raunakd11 . Whenever you see  and  on the GMAT™, you should be thinking of one of three conditions:

1) It is used with a comma before it to join two independent clauses

2) It is used with a comma before it to add the final element of a list

3) It is used without a comma before it, unless that comma ends an embedded phrase or clause, to join two parallel items

In the sentence at hand, the third condition applies in the following manner:

Glaciers that are seated in deep submarine  basins  are vulnerable  to small changes in ocean temperature, such as those that occurred over the 20th century,  and   have been rapidly retreating   in the last decades.

The shell of the sentence conveys that glaciers of a certain type  are vulnerable   and   have been rapidly retreating . We cannot join the two parallel elements without  and . The comma before the conjunction simply helps to rope off the  such as  interrupter.

I hope that helps. If you have further questions, feel free to ask.

- Andrew

pqhai · Answer

IMO, E

Glaciers that are seated in deep submarine  basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, have been rapidly retreating  in the last decades.

(A)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, have been rapidly retreating
Wrong. The structure is not parallel. X that  are seated. .... are vulnerable ....... , have been rapidly retreating .... ==> We need " and " before "have been".

(B)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, have been rapidly retreated
Wrong. Same as A. X that  are seated ..... are vulnerable ....... , have been  rapidly retreated....==> We need "and" before "have been".

(C)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, and are rapidly retreating
Wrong. The meaning is wrong, The  Glaciers are not retreating  (progressive tense), but they have been retreating (perfect progressive), because the  action "retreating" initiated in the past  ( in last decades ).
 
(D)basins, vulnerable to small changes in ocean temperature,  occurred  over the 20th century and have been rapidly retreating
Wrong. "occurred...." is not clear. It may modify "changes" or "Glaciers".

(E)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, and have been rapidly retreating
IMO, correct. The structure is: X that  are seated ...  are vulnerable ..... and have been  rapidly retreating.....in the last decades.

Waiting for OA.

jlgdr · Answer

Between C and E we need have been past perfect as correct verb form to show that this beganin the past and continues to be he case in the present. Hence E is the best answer choice

Hope it helps
Cheers
J

raunakd11 · Answer

Hello!
Can you please explain why 'and' is used, exact reason for using that word.

Thanks alot!

aditijain1507 · Answer

There are gmat questions which have a list but no comma before the last and+element. what about them  AndrewN ?

aditijain1507 · Answer

There are gmat questions which have a list but no comma before the last and+element. what about them  AndrewN ?

ExpertsGlobal5 · Answer

Hello  aditijain1507 ,

We hope this finds you well.

To answer your query, the only lists that feature a conjunction without a comma before it are lists that have only two elements; if a list has three or more elements, the "comma + conjunction" construction must be used to join the last element in the list with the preceding elements.

We hope this helps.
All the best!
Experts' Global Team

AndrewN · Answer

Hello,  aditijain1507 . Feel free to share links to these questions so that I may comment on them. Sometimes when someone brings up a point about a different question, things may not be as they appear.

Thank you for thinking to ask.

- Andrew

Raman109 · Answer

Glaciers that are seated in deep submarine  basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, have been rapidly retreating  in the last decades.

Option Elimination -

(A)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, have been rapidly retreating - we need AND before have. But the usage of present perfect continuous is correct - present perfect continuous (PPC) is used to describe an action that started in the past (in the last decades), is still ongoing in the present, and may continue into the future.

(B)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, have been rapidly retreated - We need AND. Moreover, the usage of the Present perfect (PP) is wrong. A slight difference between PPC and PP is that the Present Perfect continuous emphasizes the ONGOING nature of an action (in this case they are still retreating) and the Present Perfect focuses on the COMPLETION of an action (in this case, the retreatment hasn't been completed yet). Additionally, why use passive construction? It seems they have been retreated by someone or something. Wrong.

(C)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, and are rapidly retreating - usage of ARE is wrong, as explained in A. We need Present Perfect Continuous to describe an action that started in the past (in the last decades), is still ongoing in the present, and may continue into the future.

(D)basins, vulnerable to small changes in ocean temperature, occurred over the 20th century and have been rapidly retreating - before AND there is no verb. Its a fragment. Fragment AND Clause - wrong parallelism.

(E)basins are vulnerable to small changes in ocean temperature, such as those that occurred over the 20th century, and have been rapidly retreating - perfect.

Glaciers that are seated in deep submarine basins are

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Glaciers that are seated in deep submarine basins are

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