Select the best definition of Acute appendicitis.

A. Inflammation of the peritoneum, often producing guarding and rebound tenderness. B. Inflammation of the appendix often producing migratory right-lower-quadrant pain. C. Inflammation of the gallbladder, commonly due to cystic-duct obstruction by a stone. D. Early management focused on airway, depth and extent assessment, fluids and prevention of hypothermia.