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
[{'content': 'Serotonin is synthesized from \nSelect and explain. \nA. Tryrosine, B. Alanine, C. Tryptophan, D. Glycine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Serotonin is synthesized from tryptophanRef: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 241, fig 18.10', 'role': 'assistant'}]