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
Amount of whey protein in cow milk is: 
Select and explain. 
A. 20%, B. 40%, C. 60%, D. 80%
A: 20%
Answer: A: 20% 
Explanation: 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