Refer to the Figure Showing the Responses (Right) of an ON-Center

Refer to the figure showing the responses (right) of an ON-center retinal ganglion cell to gratings of different spatial frequencies (left) .
The retinal ganglion cell depicted is most responsive to which spatial frequency?

A) Low frequency (top)
B) Medium frequency (middle)
C) High frequency (bottom)
D) Both low and high frequencies (top and bottom)
E) All frequencies equally (top, middle, and bottom)