This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'The following is a regulatory protein of muscle \nSelect and explain. \nA. Actin, B. Myosin, C. Troponin, D. All', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Troponin and tropomyosine are the regulatory proteins of the muscle Ref:Guyton and Hall textbook of medical physiology 12th edition, page number:89', 'role': 'assistant'}]