Answer:
Retinal
Explanation:
Retinal is a one of the forms of vitamin A. It is a carotenoid that bound to opsins (proteins) allowing animal vision and it is in fact the main chemical compound for vision. Retinal is the oxidized form of retinol, an active component of the visual cycle. Retinal acts by converting the energy in form of light photons into electrical impulses in the retina.