Final answer:
The cornea and the lens of the human eye are responsible for refracting light rays to focus images on the retina. The correct answer, given the options, is the lens, which fine-tunes the focus initiated by the cornea.
Step-by-step explanation:
The cornea and the lens are responsible for refracting light rays in the human eye. The cornea, being the transparent front layer of the eye, plays a significant role in focusing the light by refracting it as it enters the eye. The lens, a clear, curved structure located behind the cornea, further adjusts the focus, ensuring that light rays converge properly on the retina. The iris, although related to light intake, controls the size of the pupil and does not refract light. Hence, the structures directly responsible for light refraction are the cornea and lens.
The final answer for the structure responsible for refracting light rays in the eye is the lens when considering the options provided, as it is specifically known for adjusting the focus of light rays onto the retina. However, it is important to recognize that the cornea also significantly contributes to this process. The cornea begins the refraction process as light enters the eye, and the lens fine-tunes the focus onto the retina.