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
Cholinergic drug which acts on hea by decrease in levels of cAMP and due to opening of K+ channels is? 
Select and explain. 
A. Methacholine, B. Oxotremorine, C. Bethanechol, D. DMPP
A: Methacholine
Answer: A: Methacholine 
Explanation: Ans. 'a' i.e., Methocholine