GMAT Critical Reasoning (CR) | Re: Scientists typically do their most creative work before the

Why do scientists produce fewer creative works after they cross forty?
There are two opposing explanations:
explanation 1: loss of creative capacity
explanation 2: they have spent a long time in the field (and hence they do not have anything new to contribute).

BF2 is the explanation 2 above, and BF1 is a statement supporting explanation 2.

Hence
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