Respuesta :
I think the answer will be A f(a+b), because it is f(a) + f (b) , not f(a) *f (b). So it is not C. And B is impossible. :)
The answer is a because if fa t fb is equivalent to an answer choice a is the same method just rewritten as a+b times 4 another way to help you is just to fill the letters in with numbers its choice a your welcome :]