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
Which one of the following combination is wrong? 
Select and explain. 
A. Phenylalanine - Niacin, B. Trytophon - Serotonin, C. Phenylalanine - Melanin, D. Tyrosine - Epinephrine
A: Phenylalanine - Niacin
Answer: A: Phenylalanine - Niacin 
Explanation: Niacin is formed by metabolism of tryptophan. Other options are correct amino acids and their metabolic productsRef: Textbook of biochemistry for medical students, seventh edition, page no: 239