Any help guys?

The first thing that you will notice is that this a "best completes the passage" question

In the Veritas Critical Reasoning 2 book we discuss this type of problem, which is one way for the test writers to try to confound those who rely entirely on the question stem to know how to approach a problem.

You can tell how to approach this type of question based on the wording before the blank...in this case the wording is "supporting this explanation is the finding that___" You can tell that this correct answer will be a premise that supports the conclusion. So treat this one as a strengthen question.

The conclusion that we are trying to support is that the cause of the fact that most scientists do their most creative work before 40 is not their age but that they have been in the field for many years. We are looking for a premise that supports this as the conclusion (cause).

Choice B supports this because it states that those few people who do their creative work after age 40 are those who have not been in the field as long.

Answer choice D says that scientists over age 40 find satisfaction in other activities. This would not strengthen the conclusion that time in the profession is the cause - because this offers another cause which is that older scientists have more of "a life" outside of work!

Hope this helps!

I'd also add that by looking at this you want to read the two statements. The first mentions a hypothesis that is believed to be true, however, the second mentions that there may be another cause to this occurrence, that the initial hypothesis is not correct and there is another reason for this phenomenon.

B provides a proper explanation as it mentions that there are a number of scientists who enter late in the field to provide creative work in their later ages.