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: Physiology
[{'content': "Actin's active site is covered by \nSelect and explain. \nA. Myosin, B. Tropomyosin, C. Troponin, D. Desmin", 'role': 'user'}, {'content': 'Answer: B \nExplanation: The active site of actin in skeletal muscles is where myosin binds. This is covered by Tropomyosin.', 'role': 'assistant'}]