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: Biochemistry
[{'content': 'The most important role of cholesterol is: \nSelect and explain. \nA. It is a component of cell membrane, B. It is a precursor of polyunsaturated fatty acids, C. It stores up energy, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]