**Core Concept:** Accommodation is the process by which the lens of the eye changes its shape to focus light onto the retina, allowing for clear vision of near objects. This process is achieved through the alteration of the lens's thickness and curvature.

**Why the Correct Answer is Right:** In the human eye, accommodation occurs due to the contraction of the ciliary muscles surrounding the lens. These muscles are innervated by the ciliary motor nucleus, which receives parasympathetic input from the oculomotor nucleus in the brainstem and sympathetic input from the preganglionic fibers of the sympathetic chain. The contraction of these muscles causes the zonules (connective fibers that hold the lens in place) to tighten, increasing the lens's thickness and curvature, which in turn leads to a change in focal length and improved vision for near objects.

**Why Each Wrong Option is Incorrect:**

A. The correct answer is not related to the lens's shape change during accommodation. This option is incorrect because it does not address the role of the ciliary muscles in changing the lens's thickness and curvature.

B. This option also does not address the correct mechanism of accommodation. While the ciliary body plays a role in iris contraction, it does not directly contribute to lens shape change during accommodation.

C. Similar to option B, the cornea's role in accommodation is incorrect because it does not involve changing the lens's thickness and curvature. The cornea primarily focuses light upon entering the eye.

D. This option is incorrect as the trabecular meshwork is part of the uveal tract and is involved in aqueous humor outflow, not accommodation.

**Clinical Pearl:** Adequate accommodation is essential for clear vision at various distances. In the elderly or individuals with cataracts, reduced accommodation can lead to presbyopia or farsightedness, respectively. Understanding the process of accommodation is crucial for diagnosing and managing these conditions.