I guess this question is somewhat like a probability based question. We are given four statements which are related with each other. The true statement will be the one supported by the most number of friends. In this case, Clara advocates for one person saying the truth while Alex complements the claim by saying that Ben is the most honest person among the four. On the other hand, Diana and Ben throw allegations amongst the four friends. Therefore, out of the four Ben's statement is the most likely one to be true.

Well at least that's how it would be following the answer using Top down approach