What is the evidence that certain types of feature detectors operate in the human visual cortex?

a. When you examine Mooney faces, at first you see only meaningless blobs, but with time and effort you start to perceive faces.

b. After you stare at a waterfall or other steadily moving display, you see stationary objects as moving in the opposite direction.

c. An electrode traveling through a section of the cortex may encounter one neuron after another with receptive fields in the same orientation.

d. Children who are deprived of input in one eye become attentive only to the other eye.