Approximately seventy-five percent of the global freshwater supply is

Approximately seventy-five percent of the global freshwater supply is stored in glaciers, which cover roughly ten percent of land area.

B. is stored in glaciers, which covers roughly ten percent of land area.

Dear Friends,

Here is a detailed explanation to this question-



Choice A: This answer choice maintains proper subject-verb agreement throughout the sentence and appropriately links the independent and dependent clauses with a comma followed by the word "which". Thus, this answer choice is correct.

Choice B: This answer choice features a subject-verb disagreement between the noun "glaciers" and the verb "covers". Thus, this answer choice is incorrect.

Choice C: This answer choice repeats the error seen in Option B. Additionally this answer choice incorrectly precedes "that" with a comma. Thus, this answer choice is incorrect.

Choice D: This answer choice features a subject-verb disagreement between the noun "seventy-five percent" and the verb "are". Thus, this answer choice is incorrect.

Choice E: This answer choice repeats the subject-verb disagreements seen in Options D, B, and C. Thus, this answer choice is incorrect.

Hence, A is the best answer choice.

To understand the concept of "Which v/s That on GMAT", you may want to watch the following video (~2 minutes):



To understand the concept of "A Rare Case when That is Preceded by a Comma on GMAT", you may want to watch the following video (~1 minute):



All the best!
Experts' Global Team

Hi, let me attempt:
which after a comma almost always refers to the noun immediately preceding it. In this case which refers to glaciers (plural noun). Therefore, singular verb covers is wrong.
Hope the explanation is helpful!

We have a Noun Phrase , so singular verb .Furthermore which touches the noun glaciers so plural verb