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': 'Which of the following contains site of attachment of calcium ions that initiates muscle contraction? \nSelect and explain. \nA. Troponin I, B. Troponin T, C. Troponin C, D. Myosin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Troponin T binds the troponin components to tropomyosin; troponin I inhibits the interaction of myosin with actin; and troponin C contains the binding sites for the Ca2+ that helps to initiate contraction.\nGanong 23 rd ed, pg 96', 'role': 'assistant'}]