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: Pharmacology
Which of the following is a  K+ channel opener ? 
Select and explain. 
A. Nifedipine, B. Minoxidil, C. Enalapril, D. Atenolol
B: Minoxidil
Answer: B: Minoxidil 
Explanation: None