The answer is B. The meaning of the adverb as well as is also, in addition or too. In (B) The student, the teacher also, want to go to the museum. In (A) as well as the teacher is between brackets, which means it is separated from the main part, so the verb should be wants: The student wants. In (C) it should be The student and the teacher want... And in (D) Also, the verb should be want.
