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: Microbiology
[{'content': 'Which of the following organism requires tryptophan for growth - \nSelect and explain. \nA. H. influenza, B. Vibrio, C. Gonococci, D. Salmonella typhi', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Salmonella typhi", 'role': 'assistant'}]