This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tryptophan metabolism detail, Subject name: Biochemistry
5-hydroxyindoleacetate is a catabolic product of 
Select and explain. 
A. Histidine, B. Tyrosine, C. Phenylalanine, D. Tryptophan
D: Tryptophan
Answer: D: Tryptophan 
Explanation: 5-hydroxyindoleacetate (5-HIAA) is a catabolic product of serotonin, which is derived from tryptophan.