This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Musculoskeletal  disorders, Subject name: Pediatrics
Duchnne's muscular dystrophy 
Select and explain. 
A. X-linked dominant, B. X-linked recessive, C. Autosomal dominant, D. Autosomal recessive
B: X-linked recessive
Answer: B: X-linked recessive 
Explanation: Duchene muscular dystrophy is a X linked recessive disorder. Usually become symptomatic before 5 yr and may have history of delayed walking