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
All of the following are the causes of sudden increase in pain in osteochondroma, except - 
Select and explain. 
A. Sarcomatous change, B. Fracture, C. Bursitis, D. Degenerative changes
D: Degenerative changes
Answer: D: Degenerative changes 
Explanation: Osteochondroma usually presents as a painless swelling.
The occurrence of pain suggests some complications such as :
Bursitis at the tip of the swelling.
Fracture through the stalk of the osteochondroma
Impingement on or tethering of neighbouring structures such as a tendon, muscle or nerve.
Malignant transformation