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: Orthopaedics
A 20 year old young patient has sclerotic lesion at diaphysis, most likely diagnosis 
Select and explain. 
A. Osteosarcoma, B. Ewing's sarcoma, C. Osteoid osteoma, D. Osteochondroma
C: Osteoid osteoma
Answer: C: Osteoid osteoma 
Explanation: None