The human eye is a relatively recent development of nature—it evolved

Cool sentence.

Some people would want to eliminate A, based on the fact that which is not directly touching the noun "eyes". However, this is a common mistake, because "primitive eyes of the pre-mammalian synapsids" is a whole noun phrase. Therefore, "which" is correctly modifying "eyes.

In summary

A) which had themselves previously evolved --- CORRECT, and good use of past perfect tense, as this evolution happens before the other evolution from the primates.
B) previously evolving themselves --- The use of the adverbial phrase -ING is incorrect, as it does not give the correct tense. The -ing is mostly used for consequences or explanations.
C) themselves having evolved previously --- "having evolved" does give you an indication of a past tense, but it does not set this action before the other past tense "had in turn evolved over many generations".
D) having been previously evolved themselves ------ "been evolved" by whom?
E) previously themselves being evolved ------ wrong tense

Dear Friends,

Here is a detailed explanation to this question-


Choice A: Option A utilizes the correct tense, past perfect, in the verb phrase "had themselves previously evolved". Thus, Option A is correct.

Choice B: Option B utilizes the incorrect tense in the verb phrase "previously evolving". Thus, Option B is incorrect.

Choice C: Option C utilizes the incorrect tense in the verb phrase "having evolved previously". Thus, Option C is incorrect.

Choice D: Option D utilizes the incorrect tense in the verb phrase "having been previously evolved". Option D also uses the passive voice which often makes an answer choice wordier than it needs to be. Thus, Option D is incorrect.

Choice E: Option E utilizes the incorrect tense in the verb phrase "previously themselves being evolved". Moreover, the use of “being” to refer to a state of existence also makes Option E quite awkward. Thus, Option E is incorrect.

Hence, A is the best answer choice.

In this sentence, the past perfect is the correct tense to use because it describes one event, the evolution of the primitive eyes of the pre-mammalian synapsids, which took place before another event, the evolution of the eyes of earlier primates.

To understand the concept of “Past perfect Tense and the use of ‘Had’ on GMAT”, you may want to watch the following video (~2 minutes):



To understand the concept of “Use of ‘Being’ on GMAT”, you may want to watch the following video (~1 minute):



All the best!
Experts' Global Team