This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
[{'content': 'Thrombosthenin is a \nSelect and explain. \nA. Coagulation factor, B. Contractile protein, C. A thrombosis promoting protein, D. A protein regulating platelet production', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Thrombasthenin, platelet contractile proteins contract and help in clot retraction 48 hours after injury. The contractile protein of platelets is, responsible for clot retraction, platelet aggregation, and release of ADP and other biologic amines essential to platelet function.', 'role': 'assistant'}]