Final answer:
The ciliary muscle is responsible for controlling the shape of the lens to focus light on the retina, which is called accommodation. It plays no direct role in controlling the amount of light reaching the retina, production of aqueous humor, or eye movement.
Step-by-step explanation:
The ciliary muscle plays a crucial role in the focusing mechanism of the eye, a process known as accommodation. Specifically, the ciliary muscle controls the shape of the lens to adjust the focal length, thereby ensuring that light entering the eye is properly focused on the retina regardless of whether an object is near or far. When considering the options provided, the correct answer is that the ciliary muscle:
- Control the amount of light reaching the retina.
- Control the shape of the lens.
The other functions listed, such as controlling the production of aqueous humor or moving the eyeball, are not directly related to the ciliary muscles' primary function of adjusting the lens shape. Therefore, the most accurate answer to the student's question is 2) control the shape of the lens.