In the human brain, a great deal of synaptic pruning occurs in the first few years of development. This pruning appears to be:
a. Reflective of the fact that the cortex is slowly taking over responsibility for functions that have previously been controlled by other parts of the brain
b. Due to an imbalance of important nutrients, and especially to low levels of the B vitamins in many children’s diets
c. An adaptive process that allows children to deal more efficiently with their environment
d. The unfortunate result of insufficiently stimulating home and school environments