This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hand Injuries, Subject name: Orthopaedics
[{'content': 'Bennet fracture dislocation involves base of - \nSelect and explain. \nA. 1st metacarpal, B. 5th metacarpal, C. 1st metatarsal, D. 5th metatarsal', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is \'a\' i.e., 1st metacarpal * Benett\'s fracture is an intra-articular fracture dislocation of the palmar base of first metacarpal bone of the thumb with either subluxation or dislocation of first carpometacarpal joint, i.e. trapezometacarpal joint. The common mechanism of injury is an axial blow directed against the partially flexed metacarpal, in most cases during "Fist fights". Patient complains of pain, swelling and tenderness over the base of the thumb. Movements of thumb are restricted.', 'role': 'assistant'}]