Select the best definition of Small-bowel obstruction.

A. Inflammation of the gallbladder, commonly due to cystic-duct obstruction by a stone. B. Mechanical or functional blockage causing pain, vomiting, distension and reduced passage of stool or flatus. C. Surgical removal of the spleen, increasing long-term risk from encapsulated bacteria. D. Early management focused on airway, depth and extent assessment, fluids and prevention of hypothermia.