The highly vascular layer of the eye that absorbs light rays and nourishes the retina is the:

The choroid is the highly vascular layer of the eye that plays a critical role in absorbing light rays and nourishing the retina. This layer is located between the retina and the sclera, and it is rich in blood vessels that supply essential nutrients and oxygen to the outer layers of the retina. The presence of these blood vessels is crucial for maintaining the health of the retinal cells, which are responsible for detecting light and enabling vision.

The choroid contains pigment that helps absorb excess light, preventing it from scattering within the eye, which enhances visual clarity. This absorption of light is essential for proper visual function, as it allows the photoreceptor cells in the retina to respond optimally to incoming light.

The other layers mentioned, such as the sclera, iris, and macula, have different roles. The sclera serves as the eye's white protective outer layer, the iris controls the size of the pupil and thus the amount of light entering the eye, and the macula is responsible for high-acuity vision but does not have the same vascular function as the choroid. Thus, the choroid is uniquely suited to both absorb light and provide nourishment to the retina, making it the correct answer.