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
Conversion of norepinephrine to epinephrine occur by: 
Select and explain. 
A. Methylation, B. Decarboxylation, C. Oxidation, D. Sulphation
A: Methylation
Answer: A: Methylation 
Explanation: None