This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Metabolites of tryptophan can give rise to: 
Select and explain. 
A. Diarrhoea, B. Vasoconstriction, C. Flushing, D. All
D: All
Answer: D: All 
Explanation: Trytophan is an essential amino acid and is precursor of Serotonin, Melatonin & Niacin.Clinical effects of Serotonin or 5Htase: Symptoms occur due to effect on smooth muscle. Cutaneous vasomotor episodes of flushing.- Potent vasoconstriction.- Chronic diarrhoeaRespiratory distress & bronchospasm.Albinism accompanies defective melanine, product of tyrosine biosynthesis