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: Biochemistry
Reaction occuring in conversion of norepinephrine to epinephrine? 
Select and explain. 
A. Hydroxylation, B. Oxidation, C. Glucuronidation, D. Methylation
D: Methylation
Answer: D: Methylation 
Explanation: Ans. D. Methylation