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
True statement regarding Nitric oxide is : 
Select and explain. 
A. NO is synthesized from arginine, B. NO is spontaneous produced from NO2, C. NO causes vasoconstriction, D. NO is released from mitochondria
A: NO is synthesized from arginine
Answer: A: NO is synthesized from arginine 
Explanation: A i.e. NO is synthesized from arginine