After observing a moth that is camouflaged against dark-colored bark, a scientist asks a question. the scientist discovers that the question has already been asked and answered by several investigations. what should the scientist do?
the scientist should test the question anyway.
the scientist should broaden the scope of the question.
the scientist should come up with a new way to test the question.
the scientist should revise the question to address a gap in knowledge.

Hello there!

If the question has been answered by several investigators, there is a high chance that there is already a good model that describes the moth.

But anyway, the scientist should revise the question to address a gap in knowledge, and see if he/her can do something to improve the knowledge in this particular subject.

If the scientist don't find anything that can be improved, there is no actual reason to lost time and resources in test something that has already been tested and is fully described (actually is useful to test something a lot of times, to see if different investigators obtain the same results, but in this case this question already has been answered by many investigators)

so the right answer is: "The scientist should revise the question to address a gap in knowledge"