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': 'The site where myosin heads bind to actin in skeletal muscles are covered by: \nSelect and explain. \nA. Tropomyosin, B. Troponin, C. Calcium, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Tropomyosin', 'role': 'assistant'}]