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: Surgery
LES sphineter is relaxed by - 
Select and explain. 
A. Nitrates, B. HL blockers, C. Morphine, D. All
A: Nitrates
Answer: A: Nitrates 
Explanation: Answer is 'a' i.e. Nitrates