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: Social & Preventive Medicine
[{'content': 'Amount of whey protein in cow milk is: \nSelect and explain. \nA. 20%, B. 40%, C. 60%, D. 80%', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ratio of whey to casein protein in cow milk is 20%:80% while in human milk it is 60%:40%. Ref: Nutrition and Child Development, K.E. Elizabeth, 4th edition pg: 17', 'role': 'assistant'}]