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 following is a microfilament ? \nSelect and explain. \nA. Tubulin, B. Actin, C. Desmin, D. Vimentin', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Actin", 'role': 'assistant'}]