The correct response is this: NATURAL SELECTION FAVORED THE EVOLUTION OF LARGER BRAINS, THIS SUGGESTS THAT THE BENEFITS OF LARGE BRAIN OUTWEIGHS THE COSTS.
In fossils record, the shift from Australopithecus to homo is characterized by larger body and brain sizes and all through subsequent evolution, brain size has to continue to get bigger. The possession of large brain make man to be much more advanced in thinking than all other animals.