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': "Fat provides ____________ of body's calories \nSelect and explain. \nA. 40%, B. 30%, C. 50%, D. 75%", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]