A patient has suffered a cerebral hemorrhage that has caused dysfunction of the precentral gyrus of his right cerebral cortex. As a result, (a) he cannot voluntarily move his left arm or leg, (b) he...

A patient has suffered a cerebral hemorrhage that has caused dysfunction of the precentral gyrus of his right cerebral cortex. As a result, (a) he cannot voluntarily move his left arm or leg, (b) he feels no sensation on the left side of his body, (c) he feels no sensation on his right side.

A number of brain structures are listed below. If an area is primarily gray matter, write a in the answer blank; if mostly white matter, respond with b.