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
Mallet finger is: 
Select and explain. 
A. Avulsion fracture of extensor tendon of distal phalanx, B. Fracture of distal phalanx, C. Fracture of middle phalanx, D. Fracture of proximal phalanx
A: Avulsion fracture of extensor tendon of distal phalanx
Answer: A: Avulsion fracture of extensor tendon of distal phalanx 
Explanation: Ans: a (Avulsion fracture of extensor tendon of distal phalanx)Ref: Maheshwari Ortho, 3rd ed, p. 100