This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amino Acids Basics, Subject name: Biochemistry
[{'content': 'Which of the following is not an essential amino add? \nSelect and explain. \nA. Methionine, B. Tryptophan, C. Leucine, D. Alanine', 'role': 'user'}, {'content': 'Answer: D \nExplanation: ANSWER: (D) AlanineREF: Harper 27th ed chapter 3Repeat Biochemistry December 2010', 'role': 'assistant'}]