Verbal | Re: GMAT Set 30 - 5

A answer choice may be eliminated for pronoun ambiguity if another answer choice avoids the ambiguity and is free of errors.
In B and E, they has two eligible antecedents (economists and users).
Since A avoids this issue and is free of errors, eliminate B and E.
In C, are replacing lacks a subject.
Eliminate C.
In D, it lacks a viable referent.
Eliminate D.
The correct answer is A.

There are 2 prepositions that are confusing – when and “in which” and the confusion is when both of
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