Please review the first sentence of the stimulus.
Critics claim that it is required that we can indicate how the public will benefit.
The scientist disagrees with that requirement, which is why (E) is the correct answer.
(A) says that public benefit is irrelevant. There are two reasons why that does not describe the scientist's position.
First, the scientist disagrees that public benefit is a requirement. He doesn't say it's irrelevant. For instance, the scientist could believe that public benefit is a sufficient reason, even though it's not a necessary reason.
Second, the scientist didn't say that public benefit is irrelevant. He only said that being able to specify the benefit is not a requirement. In other words, the disagreement between the critics and the scientist is about whether it's necessary to be extremely specific about how the public will benefit.