Select the best definition of Acute limb ischaemia.

A. A rapidly progressive infection causing fascial and tissue necrosis and requiring urgent surgery. B. Early management focused on airway, depth and extent assessment, fluids and prevention of hypothermia. C. Mechanical or functional blockage causing pain, vomiting, distension and reduced passage of stool or flatus. D. A sudden fall in limb perfusion causing pain, pallor, pulselessness and neurological compromise.