Question on Pase perfect/Past tense

[aaggar7]

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

Here,we are talking of two actions that took place in past "led" and "had existed".So is the usage of past perfect tense "had existed" incorrect?

[Nachiket]

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

Here,we are talking of two actions that took place in past "led" and "had existed".So is the usage of past perfect tense "had existed" incorrect?

It should be simple past tense.

My pick B.

Usage of Past Perfect makes more sense when the sequence of events is ambiquious in the sentence.
In such scenarios, we use past perfect to remove the ambiquity.

[Lifetron]

https://www.beatthegmat.com/in-which-vs- ... 71140.html