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': 'Mallet finger is: \nSelect and explain. \nA. Avulsion fracture of extensor tendon of distal phalanx, B. Fracture of distal phalanx, C. Fracture of middle phalanx, D. Fracture of proximal phalanx', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: a (Avulsion fracture of extensor tendon of distal phalanx)Ref: Maheshwari Ortho, 3rd ed, p. 100', 'role': 'assistant'}]