This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Muscle Physiology, Subject name: Physiology
The nerve impulse which leads to initiation of smooth muscle contraction 
Select and explain. 
A. Cause opening of the calcium channel which leads to increase in Ca+2 contraction, B. Cause both plasma membrane and T - tubules to undergo depolarisation, C. Inhibits Na+ entry in sarcomere, D. Is initiated by binding of acetylcholine to receptors in sarcoplasmic reticulum
A: Cause opening of the calcium channel which leads to increase in Ca+2 contraction
Answer: A: Cause opening of the calcium channel which leads to increase in Ca+2 contraction 
Explanation: Ans. (a) Cause opening of the calcium channel which leads to increase in Ca2+ contraction(Ref: Ganong, 25th ed/p.116)The never impulse which leads to initiation of smooth muscle contraction Cause opening of the calcium channel which leads to increase in Ca2+ contraction