This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Severe disease involves 
Select and explain. 
A. Lunate, B. Tibial tubercle, C. Calcaneum, D. Navicular
C: Calcaneum
Answer: C: Calcaneum 
Explanation: Ans. is 'c' i.e., Calcaneum