We Can Conclude That Natural Selection Must Have Acted in Favor

We can conclude that natural selection must have acted in favor of large brains in humans because:

A) we have large brains in proportion to our body size compared to other mammals.
B) large brains have allowed us to dominate the planet.
C) large brains are metabolically expensive to produce and maintain.
D) we would have large brains whether or not natural selection favored them.
E) None of the answer options is correct.