Correct option is A
Explanation-
In the retina, rod cells (as well as cone cells) release the neurotransmitter glutamate in the dark. In darkness, photoreceptor cells (rods and cones) are depolarized and continuously release glutamate. When light strikes the outer segment of the rods:
Phototransduction occurs → cells become hyperpolarized.
This causes a reduction in glutamate release. This decrease in glutamate release is crucial for signaling the presence of light to bipolar and ganglion cells in the retina.
Incorrect Options-
Acetylcholine (Option b): Mostly used by certain amacrine cells, not the primary neurotransmitter in rods.
GABA (Option c): Inhibitory neurotransmitter used by horizontal and amacrine cells, not rods.
Glycine (Option d): Another inhibitory neurotransmitter found in specific retinal interneurons, not rods.
Final Answer:
Glutamate (Option a) is the neurotransmitter whose release decreases when light hits the rods in the retina.
