This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
Serotonin is derived from 
Select and explain. 
A. Tyrosine, B. Tryptophan, C. Phenylalanine, D. Methionine
B: Tryptophan
Answer: B: Tryptophan 
Explanation: Serotonin is a metabolite of tryptophan Tryptophan ------------------->5hydroxy tryptophan ------------------>5hyroxy tryptamine (serotonin )Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 241