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: Physiology
cGMP acts as second massenger for ? 
Select and explain. 
A. Nitric acid, B. FSH, C. Dopamine, D. Calcitonin
A: Nitric acid
Answer: A: Nitric acid 
Explanation: Ans. is 'a' i.e., Nitric acidActivation of GC (Guanylyl cyclase) results in increased synthesis and intracellular accumulation of cGMP.cGMP acts through cGMP dependent protein kinase.Hormone acting through cGMP are atrial natriuretic peptide and nitric oxide.