This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
cardiomyopathy absent in ? 
Select and explain. 
A. DMD, B. Becker Dystrophy, C. Myotonic Dystrophy, D. Myasthenia Gravis
B: Becker Dystrophy
Answer: B: Becker Dystrophy 
Explanation: ref harrisons21st ed