Greenough's Research Indicated That One of the Proteins Needed for the Development

Greenough's research indicated that one of the proteins needed for the development of the visual system is controlled by a gene whose action does not occur without visual experience. This finding leads to the conclusion that some maturational sequences

A) are purely automatic.
B) require programmed exercises from infancy on.
C) are actually the result of learning.
D) require some experience to trigger them.
E) are exclusively the result of genetics.