Question

A ganglion cell receiving input from ___has the smallest receptive field.
A) rods in the periphery of the retina
B) rods 20 degrees from the fovea
C) cones in the fovea
D) cones outside the fovea

Answer 1

Taken from Visual Receptive Fields section of the Scholarpedia article 4(1):5393.

Receptive fields of ganglion cells increase as we move away from the fovea, giving poor resolution away from the center of focus (which is why you can't read most of a paragraph if you're concentrating on a single point at the paragraph's center)

This happens because number of cones a ganglion cell is in contact with (at the fovea) can be as small as one, but number of rods in contact with ganglion cells is relatively large (larger if away from fovea). Hence in the case of rod-bipolar cell contact, this has the effect of averaging out detail.

More rods connected to a single ganglion cell means more field of view which can elicit a change in the nerve response (by changing light intensity in this field). A measure of this field of view is nothing but size of receptive field.

C.