This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Phenylalanine and Tyrosine metabolism Detail, Subject name: Biochemistry
All of the following are tyrosine derivatives, EXCEPT 
Select and explain. 
A. Serotonin, B. Melanin, C. Epinephrine, D. Thyroxine
A: Serotonin
Answer: A: Serotonin 
Explanation: Melanin, Catecholamines (Dopamine, Norepinephrine, Epinephrine), Thyroxine are the derivatives are tyrosine. Serotonin is a tryptophan derivative.