Concept: This question tests your understanding of the functions of the autonomic nervous system, specifically distinguishing between the actions of the sympathetic and parasympathetic nervous systems.

Why (B) is correct: The parasympathetic nervous system is often referred to as the "rest and digest" system. One of its key functions is to promote relaxation and conserve energy. Constriction of the pupil (miosis) is a parasympathetic response, allowing for focusing on near objects and reducing light entry.

Why other options are wrong:

• (A) Acceleration of heartbeat: This is a function of the sympathetic nervous system, which prepares the body for "fight or flight."
• (C) Stimulation of sweat gland: This is primarily a function of the sympathetic nervous system, involved in thermoregulation during stress or exertion.
• (D) Contraction of erector pili: This causes goosebumps and is a function of the sympathetic nervous system, often in response to cold or fear.

Common Mistake: Students often confuse the "fight or flight" responses (sympathetic) with the "rest and digest" responses (parasympathetic).

NEET Tip / Mnemonic: Remember Parasympathetic = Peace (rest and digest), while Sympathetic = Stress (fight or flight).

Correct Answer: (B)