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
Basic pathology in myositis ossificans progressiva is in? 
Select and explain. 
A. Muscle fibres, B. Serum chemistry, C. Body collagen, D. None of the above
A: Muscle fibres
Answer: A: Muscle fibres 
Explanation: Moality in fibrodysplasia ossificans progressiva (myositis ossificans progressiva) is usually related to restrictive lung disease caused by an inability of chest to expand. Ref: Harrison 17/e, Page 2416; Tachdjian's Pediatric Ohopedics 3/e, Page 1632-38; watson Jones 6/e, Page 63.