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
Tryptophan is 
Select and explain. 
A. Glucogenic, B. Ketogenic, C. Both glucogenic & ketogenic, D. None
C: Both glucogenic & ketogenic
Answer: C: Both glucogenic & ketogenic 
Explanation: During metabolism Tryptophan, pa of carbon skeleton enters ketogenic pathway and rest glucogenic pathway. Alanine is glucogenic and Acetoacetyl CoA is ketogenic.