GMAT CLUB OLYMPICS: Decades of research conducted by leading psycholog

Explanation:

Meaning + Pronouns + Subject-verb Agreement + Redundancy/Awkwardness

Understanding the intended meaning is key to solving this question; the intended core meaning of this sentence is that of the mental health issues to which today’s population is subject, many individual issues among them stem from social isolation.

A. Trap. This answer choice incorrectly uses the singular verb “stems” to refer to the plural noun “issues”. Further, Option A incorrectly uses the term “much” to refer to the countable noun “issues”; for a noun such as “issues”, the appropriate equivalent term is “many”.

B. Trap. This answer choice incorrectly uses the term “much” to refer to the countable noun “issues”; for a noun such as “issues”, the appropriate equivalent term is “many”.

C. This answer choice incorrectly uses the singular verb “stems” to refer to the plural noun “issues”. Further, Option C incorrectly uses the term “much” to refer to the countable noun “issues”; for a noun such as “issues”, the appropriate equivalent term is “many”. Additionally, Option C uses the needlessly wordy phrase “issues that are related to mental health”, rendering it awkward.

D. Correct. This answer choice correctly uses the plural verb “stem” to refer to the plural noun “issues”. Further, Option D correctly uses the term “many” to refer to the countable noun “issues”. Additionally, Option D is free of all awkwardness and redundancy.

E. This answer choice uses the needlessly wordy phrase “issues that are related to mental health”, rendering it awkward.

D is the best answer choice.