Answer AND Explanation:
The retina is a light sensitive layer that contains both rods and cones. The cones contain a photochemical pigment called iodopsin which perceives light of high intensity. Greater concentrations of cones occurs in the fovea centralis which is by far the most used region of the retina. Rods contain a photochemical pigment called rhodopsin which perceives light of low intensity but is not sensitive to color. Rods are in greater concentration round the periphery of the retina and are absent in the fovea centralis.