The correct option is C Cornea
The wall of the eyeball is composed of three layers. The external layer is composed of a dense connective tissue and is called the sclera. The sclera is a well vascularized layer, except the anterior portion, which is called the cornea. The cornea has no blood vessels. The middle layer, choroid, contains many blood vessels and looks bluish in color. The inner layer is the retina and the retina is supplied by the central retinal artery and the posterior ciliary arteries.