This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Muscle, Subject name: Physiology
[{'content': 'The ratio of actin : troponin : tropomyosin molecules in an thin filament is: \nSelect and explain. \nA. 1:01:01, B. 1:03:05, C. 1:07:07, D. 7:01:01', 'role': 'user'}, {'content': 'Answer: D \nExplanation: A thin filament has 3 molecules - actin troponin tropomyosin in a ratio of 7: 1: 1.', 'role': 'assistant'}]