Which part of the eye provides nourishment to the retina?

The choroid is the correct answer because it is a layer of blood vessels and connective tissue located between the retina and the sclera (the white part of the eye). Its primary function is to supply nutrients and oxygen to the retina, which is essential for maintaining the health and function of the retinal cells. The choroid contains a rich network of blood vessels that ensure the retina receives adequate nourishment, enabling it to perform its critical role in vision, particularly in the detection of light and the processing of visual information.

The iris, while important for regulating the amount of light that enters the eye, does not play a direct role in nourishing the retina. The cornea serves primarily as a transparent outer layer that focuses light into the eye and does not provide nutritional support. The limbus is the border area between the cornea and the sclera, and it contains stem cells that help maintain the corneal epithelium but is not involved in nourishing the retina either. Hence, the choroid stands out as essential for this specific function.