This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pharmacology
Which of the following is a potassium channel opener? 
Select and explain. 
A. Nicorandil, B. Ranolazine, C. Ivabradine, D. Nitroprusside
A: Nicorandil
Answer: A: Nicorandil 
Explanation: Ans. (A) Nicorandil(Ref: Harrison 12th/1862)Nicorandil is the agent that causes coronary dilation by activating myocardial ATP sensitive K+ channels. Inaddition it possesses NO releasing property; to which tolerance does not develop.