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: Physiology
Curdling of milk is caused by - 
Select and explain. 
A. Rennin, B. Lipase, C. Amylase, D. Elastase
A: Rennin
Answer: A: Rennin 
Explanation: Ans. is'a'i.e., Rennin [Ref: Concise oxford dictionary p. 1218iRennin is an enzyme secreted into the stomach of unweaned mammis causing the curdling of milk.