Japhet knows that while rods are spread throughout the retina, cones are concentrated around the fovea. from this knowledge, what might japhet infer?

Since Japhet knows that rods are spread throughout the retina and cones are concentrated around the fovea, from this knowledge, Japhet might infer that color is easier to see in the center of the visual field. Rods are sensitive to light and dark changes and are not good in color vision. Hope this answers your question.

Tta ttc ctg i hope its right.

It is evolution, because we all have some of the same traits like eye color or shape or ears.