There are two types of photoreceptor cells,  …A… and …B… . These cells contains photopigments Here, A and B refers to
a)	A-rods; B-cones	b)	A-cones; B-rhodopsin
c)	A-rhodopsin; B-rods	d)	A-rods; B-fovea

(a)

There are two types of photoreceptor cells, i.e., (i) Rods (ii) Cones

These cells contains the light-sensitive proteins called the photopigments. The daylight (photopic) vision and colour vision are the functions of cones and the twilight (scotopic) vision is the function of the rods. The rods contains a purplish-red protein called the rhodopsin or visual purple, which contains a derivative of vitamin-A. In human eye, there are three types of cones which possess their own characteristic photopigments that respond to red, green and blue lights. The sensations of different colours are produced by various combinations of these cones and their photopigments. When these cones are stimulated equally, a sensation of white light is produced