Optic nerve is formed by the axons of retinal ganglionic cells, which leaves the eye through optic disk. The two types of retinal ganglionic cells are,
1). Magnocellular (M) cells
2). Parvocellular (P) cells
The parvocellular cells receive the visual input mostly from cones and provides color vision. Magnocellular cells receive mostly from the rods (not color vision).
Thus, the blanks can be filled with parvocellular; magnocellular.