This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General, Subject name: Physiology
Mechanism of action of NO is - 
Select and explain. 
A. Through protein kinase C, B. Through IP3-DAG system, C. Through cGMP, D. Through intracellular receptors
C: Through cGMP
Answer: C: Through cGMP 
Explanation: Ans. is 'c' i.e., Through cGMP * NO acts through group IIB hormonal mechanisms, i.e. through cGMP as the second messenger.