Concept: This question tests your knowledge of the cranial nerves and their specific functions, particularly focusing on the abducens nerve.

Why (A) is correct: The abducens nerve (cranial nerve VI) is a motor nerve responsible for innervating the lateral rectus muscle of the eye. This muscle is crucial for the abduction (outward movement) of the eyeball. Therefore, injury to this nerve directly affects the movement of the eyeball, specifically its ability to move laterally.

Why other options are wrong:

• (B) Movement of tongue: The hypoglossal nerve (cranial nerve XII) controls tongue movement.
• (C) Swallowing: Swallowing involves multiple cranial nerves, including the glossopharyngeal (IX), vagus (X), and trigeminal (V) nerves.
• (D) Movement of the neck: Neck movements are primarily controlled by spinal nerves and the accessory nerve (cranial nerve XI).

Common Mistake: Students often confuse the functions of the different cranial nerves, especially those involved in eye movement (oculomotor, trochlear, abducens).

NEET Tip / Mnemonic: To remember the cranial nerves involved in eye movement, think of "LR6 SO4 All others 3". This means the Lateral Rectus muscle is innervated by cranial nerve 6 (Abducens), the Superior Oblique muscle by cranial nerve 4 (Trochlear), and all other extrinsic eye muscles by cranial nerve 3 (Oculomotor).

Correct Answer: (A)