Which of the following statements about retinal neurons is correct?单项选择题

Some horizontal cells are excitatory (using glutamate as their transmitter), other horizontal cells are inhibitory (using GABA as their transmitter).

There are many types of bipolar cell that receive input from rod photoreceptors, but only one type of bipolar cell receives input from cone photoreceptors.

Some bipolar cells (the “on bipolars”) generate action potentials, whereas other types of bipolar cells (“off bipolars”) only generate graded hyperpolarisations.

Some retinal ganglion cells are “on centre” (responding to light in the middle their receptive field), others are “off centre” (inhibited by light in the centre of their receptive field).