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
Epinephrine is most closely related in structure to: 
Select and explain. 
A. Niacin, B. Tyrosine, C. Methionine, D. Glycerol
B: Tyrosine
Answer: B: Tyrosine 
Explanation: None