sajini wrote:
The ophthalmologists' offices have begun selling prescription goggles to their customers once the nearby gymnasium had completed adding an Olympic size outdoor pool.
A. The ophthalmologists' offices have begun selling prescription goggles to their customers once the nearby gymnasium had completed adding an Olympic size outdoor pool
B. The ophthalmologists' offices began the selling of prescription goggles to their customers once the nearby gymnasium had completed adding an Olympic size outdoor pool
C. That ophthalmologists have begun the selling of prescription goggles to their customers once Olympic pool the nearby gymnasium had completed adding
D. The ophthalmologists began selling prescription goggles to their customers once the nearby gymnasium had completed adding an Olympic size outdoor pool
E. That ophthalmologists' offices began selling prescription goggles to their customers once the nearby gymnasium had completed adding an Olympic size outdoor pool
E: Fragment sentence. The 'That' relative clause could constitute a subject. However, the answer choice as a whole is missing a verb.
Past Perfect: We use the past perfect if one action in the past precedes another past action and if we need to clarify the time sequence. In this problem, the earlier past event 'had completed adding...pool' precedes the ophtalmologists' decision to sell prescription googles to their customers. In addition, the past perfect is correctly used to empahsize the order of events.
As a result, we use the past perfect for the earlier past action and a simple past tense verb for the later one. Answers A & C incorrect.
We are left with B and D:
Answer B: Wrong. 'The selling of prescription googles' is redundant in comparison with 'selling prescription googles'. Pure redundancy is always wrong on the GMAT.
Hence, D correct.