SajjadAhmad
Investment by a scientist in an established theory, especially because it has helped to attribute unobservable causes to phenomena, makes it likely to overlook gaps in the observable data or justify them too readily.A. Investment by a scientist in an established theory, especially because it has helped to attribute unobservable causes to phenomena, makes it likely to overlook gaps in the observable data or justify them too readily.
B. A scientist who is invested in an established theory, especially because it has helped to attribute unobservable causes to phenomena, makes overlooking gaps in the observable data or justifying them too readily likely when they do occur.
C. A scientist who is invested in an established theory is likely to overlook or justify too readily a gap in the observable data when it does appear, especially because it has helped to attribute unobservable causes to phenomena.
D. Scientists' being invested in an established theory, especially because it has helped to attribute unobservable causes to phenomena, makes them likely to overlook gaps in the observable data or justifying them too readily when they do appear.
E. Being invested in an established theory, especially one that has helped to attribute unobservable causes to phenomena, is likely to make scientists overlook gaps in the observable data or justify them too readily.
Source: GMAT Free
Official Explanation
Creating a filter: in the original sentence, the two instances of the pronoun "it" jump out as worthy of suspicion. The second "it" has no reference, and the first is ambiguous between "investment" and "theory." We can eliminate (A) on these grounds.
Applying the filter: choice (B) solves the problem in (A), but the wording in (B) indicates that the scientist makes gaps likely; that's contrary to the intended meaning, so (B) is out. Choice (C) has a problem with its second pronoun "it"; it's ambiguous. Choice (C) is out. Choice (D) has broken parallelism between "overlook" and "justifying." So (D) is out, and we are down to (E). Choice (E) looks good. There is no ambiguity of pronoun, and the intended meaning is clear: the investment can make scientists overlook gaps.
The correct answer is (E).