This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
Tryptophan gives rise to 
Select and explain. 
A. Thyroxine, B. Melatonin, C. Melanin, D. Epinephrine
B: Melatonin
Answer: B: Melatonin 
Explanation: Melatonin is synthesised from serotonin which in turn is from tryptophan.Ref: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 519