Rods and cones are the photoreceptor cells of the human retina. The ____A____ vision is the function of rods and ____B____ vision is the function of cones. The rods contain ____C____, which is a derivative of ____D____.

Select the correct set of A, B, C and D.

	A	B	C	D
1.	Scotopic	Photopic	Visual purple	Vitamin A
2.	Photopic	Scotopic	Visual purple	Vitamin A
3.	Scotopic	Photopic	Visual violet	Vitamin D
4.	Photopic	Scotopic	Visual violet	Vitamin D