The Age-Related Changes That Occur in Intellectual Skills Have Been

The age-related changes that occur in intellectual skills have been traced to which of the following brain changes?

A) enlargement of the cerebellum, which controls balance and some motor control
B) shrinkage of the prefrontal regions of the brain
C) build up of protein plaques around the axons in the hypothalamus
D) enlargement of the corpus callosum, which connects the left and right hemisphere, thereby making transfer of information slower