The correct answer is B. Ciliary body.
The ciliary body is a ring of muscle that surrounds the lens of the eye. It helps to adjust the focal length of the lens by contracting and relaxing. When the ciliary body contracts, it pulls the lens into a more spherical shape, which allows the eye to focus on objects that are close. When the ciliary body relaxes, it allows the lens to become more flattened, which allows the eye to focus on objects that are far away.
The lens is a transparent structure that lies behind the iris and pupil. It helps to focus light onto the retina, which is a light-sensitive tissue at the back of the eye. The retina converts light into electrical signals that are sent to the brain, which interprets them as images.
The retina is a thin layer of tissue that lines the back of the eye. It contains millions of light-sensitive cells called photoreceptors. There are two types of photoreceptors: rods and cones. Rods are responsible for vision in dim light, while cones are responsible for color vision.
The entire eyeball is a spherical structure that is filled with a clear fluid called vitreous humor. The vitreous humor helps to maintain the shape of the eyeball and cushion the delicate structures inside the eye.
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