Sentence Correction

Hi,



The correct answer is B) but I need an explanation to better understnad why B is correct..... thanks

59. His studies of ice-polished rocks in his Alpine homeland, far outside the range of present-day glaciers, led Louis Agassiz in 1837 to propose the concept of an age in which great ice sheets had existed in now currently temperate areas.
(A) in which great ice sheets had existed in now currently temperate areas
(B) in which great ice sheets existed in what are now temperate areas
(C) when great ice sheets existed where there were areas now temperate
(D) when great ice sheets had existed in current temperate areas
(E) when great ice sheets existed in areas now that are temperate

Thanks
Peer

If you don't take time to underline the portion that needs to be corrected, it gets difficult for people to answer the Q. People who try to answer will need more time to solve the problem. Please underline.

can someone explain why we use simple past tense instead of past perfect?

i would think we need past perfect since this sentence obviously states his studies and also the ice sheets existed beforehand.

The correct answer is B) but I need an explanation to better understnad why B is correct..... thanks

59. His studies of ice-polished rocks in his Alpine homeland, far outside the range of present-day glaciers, led Louis Agassiz in 1837 to propose the concept of an age in which great ice sheets had existed in now currently temperate areas.
(A) in which great ice sheets had existed in now currently temperate areas
(B) in which great ice sheets existed in what are now temperate areas
(C) when great ice sheets existed where there were areas now temperate
(D) when great ice sheets had existed in current temperate areas
(E) when great ice sheets existed in areas now that are temperate

Thanks
Peer

A is wrong because now and current mean the same and induce redundancy

Is "in which" = when?? No

When refers to an exact time ( Some one correct me if I am wrong)

in which refers to a time period

So C, D & E are out.

Had existed is wrong because there are no 2 actions here and simple past is good enough

past perfect is needed when one action happened before another in the past! for exmp: i gave her flowers, that i had brought for her! (both actions happened in the past)
so in his consept ice sheets existed and thats all. pp is not needed here.

when refers to a time period or time but "concept of age" is a concept..concept is not a time period so c,d and e goes out...

a has redundant now and current..so only option is "b"

If some people read this post, I want to precise that OG correction tells us that we can use "in which" as well as "when"...

Thanks for the explanation on the verb tense, that's clear.

Can someone please explain why "e" is wrong here ?

And why both "in which" and "when" can be used interchangeably here as per the explanation of OG-11 ?

Questions:
1) I still don't fully understand why the simple past is preferred over the past perfect. Aren't we trying to say that the ice sheets "had existed" before Louis Agassiz "led to propose in 1837?" So "led" is in the simple past and so, shouldn't "had existed" be used to indicate that the ice sheets existed before his proposal?
2) In the OG, "In which" and "when" can be used interchangeably - I thought a hypothetical time frame requires "in which"

so , finally, is there any rule which says 'when' and 'in which' are always interchangeable or there are some specific instances?

Ron, your explanations are always so clear and precisely address the source of my confusion, relieving me of the question marks I had aobve my head prior to reading your answer; we are lucky to have you as a member of this online forum Ron