Anders: The physical structure of the brain plays an important role in thinking. So researchers developing "thinking machines"-computers that can make decisions based on both common sense and factual knowledge-should closely
model those machines on the structure of the brain.

Yang: Important does not mean essential. After all, no flying machine closely modeled on birds has worked; workable aircraft are structurally very different from birds. So thinking machines closely modeled on the brain are also likely to
fail. In developing a workable thinking machine, researchers would therefore increase their chances of success if they focus on the brain's function and simply ignore its physical structure.

In evaluating Yang's argument it would be most helpful to know whether

(A) studies of the physical structure of birds provided information crucial to the development of workable aircraft
(B) researchers currently working on thinking machines take all thinking to involve both common sense and factual knowledge
(C) as much time has been spent trying to develop a workable thinking machine as had been spent in developing the first workable aircraft
(D) researchers who specialize in the structure of the brain are among those who are trying to develop thinking machines
(E) some flying machines that were not closely modeled on birds failed to work

I confused over A and B.