Explanation:
Correct Option: B. Pain out of proportion to the apparent injury, particularly pain that is intensely exacerbated by passive stretching of the muscles within the involved compartment, is universally recognized as the earliest and most sensitive clinical sign of acute compartment syndrome. The classic '6 Ps' (pain, pallor, pulselessness, paresthesia, paralysis, and poikilothermia) are often taught, but relying on them exclusively can be extremely dangerous. Pulselessness (Option A), pallor (Option C), and paralysis (Option D) are exceedingly late signs, often indicating irreversible ischemic necrosis of muscle and nerve tissue has already occurred. Diagnosis should be strongly suspected clinically based on pain profiles and confirmed with intracompartmental pressure monitoring if necessary, long before peripheral pulses disappear. (Ref: McQueen and Court-Brown, J Bone Joint Surg Br, 1996; Matsen et al., Clin Orthop Relat Res, 1975)