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: Radiology
Calcification of the interveebral disc is present in: 
Select and explain. 
A. Maple syrup urine disease, B. Homocystinuria, C. Ankylosing spondylitis, D. Achondroplasia
C: Ankylosing spondylitis
Answer: C: Ankylosing spondylitis 
Explanation: Ans. Ankylosing spondylitis