In the Human Brain,a Great Deal of Synaptic Pruning Occurs

In the human brain,a great deal of synaptic pruning occurs in early childhood. This pruning appears to be:

A) The unfortunate result of insufficiently stimulating home and school environments.
B) An adaptive process that allows children to deal more efficiently with their environment.
C) Due to an imbalance of important nutrients,and especially to low levels of the B vitamins in many children's diets.
D) The result of the fact that the cortex is slowly taking over responsibility for functions that have previously been controlled by other parts of the brain.