Scientists typically do their most creative work before the age of for

First we'll read through the argument, the first two sentences include a common misconception, and the meaning of that common misconception that the argument opposes. The second bolded phrase is evidence to support the claim the argument agrees with. The last sentence includes the conclusion "they(scientists) have simply(not) aged but rather that they generally have spent too long in a given field".

E is incorrect since the argument doesn't defend the first phrase.

A is correct about phrase 1 but phrase 2 is not an objection against the position. Nothing is defended in the argument.

B is incorrect since the second phrase doesn't support the position that phrase 1 mentions.

C is incorrect because it does not support the explanation in the first phrase.

D remains since it addresses our concerns in phrase 1 and phrase 2.

­
Situation:
Scientists typically do their most creative work before the age of forty.

Commonly believed reason for the truth:
It is commonly thought that this happens because aging by itself brings about a loss of creative capacity.

Consideration against this reason:
However, studies show that a disproportionately large number of the scientists who produce highly creative work beyond the age of forty entered their field at an older age than is usual.
By the age of forty the large majority of scientists have been working in their field for at least fifteen years

Conclusion: (the reason as per the author)
The real reason why scientists over forty rarely produce highly creative work is not that they have simply aged but rather that they generally have spent too long in a given field.
Let’s look at the options.

(A) The first is the position that the argument as a whole opposes; the second is an objection that has been raised against a position defended in the argument.

The argument does oppose what is given in first boldface. But the second boldface supports the position defended in the argument i.e. it supports the conclusion of the argument. Hence, this is not correct.

(B) The first is a claim that has been advanced in support of a position that the argument opposes; the second is a finding that has been used in support of that position.

The first can be considered a claim (aging by itself brings about a loss of creative capacity). But it is not supporting any position that the argument is opposing. The argument is opposing the claim itself that aging brings about the loss of creative capacity.

(C) The first is an explanation that the argument challenges; the second is a finding that has been used in support of that explanation.

The first is an explanation that the argument challenges. The second is a finding that has been used to oppose that explanation. It is not used in support of that explanation

(D) The first is an explanation that the argument challenges; the second is a finding on which that challenge is based.

This is correct. The first is an explanation that the argument challenges. The second is a finding from the studies on which that challenge is based.

(E) The first is an explanation that the argument defends; the second is a finding that has been used to challenge that explanation.

The argument does not defend what is given in the first boldface.

Answer (D)­

Discussion on Boldface Questions: https://youtu.be/U57vXdqujkY