This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Classification and metabolism of amino acids, Subject name: Biochemistry
The biosynthesis of Epinephrine from Norepinephrine requires 
Select and explain. 
A. Pyridoxal phosphate, B. Biotin, C. Cytochrome P450, D. S-adenosyl methionine
D: S-adenosyl methionine
Answer: D: S-adenosyl methionine 
Explanation: S-adenosyl methionine (SAM) is the methyl donor for the conversion of Norepinephrine to Epinephrine.