Concept: This question tests your knowledge of specialized sensory receptors in the skin and their specific functions, particularly mechanoreceptors and thermoreceptors.

Why (A) is correct: The End bulb of Ruffini (also known as Ruffini corpuscles or Ruffini endings) are specialized sensory receptors located in the dermis and subcutaneous tissue. They are primarily responsible for detecting heat, sustained pressure, and skin stretch. They are slow-adapting mechanoreceptors.

Why other options are wrong:

• (B) Cold: Cold is primarily detected by Krause end bulbs and free nerve endings.
• (C) Touch: Touch is detected by Meissner's corpuscles (light touch), Merkel's discs (sustained touch/pressure), and free nerve endings.
• (D) Pressure: Pressure is detected by Pacinian corpuscles (deep pressure/vibration) and Merkel's discs (sustained pressure). While Ruffini endings do detect sustained pressure, their primary association is with heat detection.

NEET Tip / Mnemonic: Remember "Ruffini for Radiant heat" or "Ruffini is Really hot" to associate them with heat detection. For others: Meissner for Mild touch, Pacinian for Pressure/vibration, Krause for Kold.

Correct Answer: (A)