What is the difference between choroid and sclera

Sclera is the white of the eye. It is the tough outer coat of the eye that covers the eyeball except for the cornea. It is the tough, opaque tissue that serves as the protective outer coat of the eye, providing structure and strength to the eye. There are six small muscles attached to the sclera that control the eye's movements. In older people, the sclera often appears yellow.

Choroid is the vascular layer of the eye lying between the retina and the sclera. It is a high flow vascular tissue that provides nourishment for the back of the eye. In addition, there are pigment cells within the choroid that absorb stray light and so it helps to lessen glare within the eye.

the answer will be a) proteins i believe