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': 'Bovine milk contains \nSelect and explain. \nA. 4% of lactose, B. 3% of lactose, C. 5% of lactose, D. 2% of lactose', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]