This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Which of the following is an effect of acetylcholine? 
Select and explain. 
A. Relaxes LES, B. Contracts LES, C. Constricts the blood vessels, D. Relaxes the bronchial muscles
B: Contracts LES
Answer: B: Contracts LES 
Explanation: Acetyl choline is a neurotransmitter ,which is a chemical released by nerve cell ir neuron .acetyl choline causes muscle to contract,activate pain responses and regulates endocrine and REM sleep functions Ref:Guyton and Hall textbook of medical physiology 12th edition,page number:77,78