Ans.
The rods and cones are defined as photoreceptor cells, present in the retina and perform visual phototransduction. The retina is innermost, light sensitive tissue layer of the eye, which is found at the back of eyeball.
The function of retina includes conversion of an optical image into nerve impulses through the regulated excitation of color sensing pigments, present at rods and cones. The excitation results in formation of a representation of external environment in the brain.
Thus, the correct answer is 'option). retina.'