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 organisms does NOT react with gram's stain? \nSelect and explain. \nA. Actinomyces israeli, B. Candida albicans, C. Mycobacterium tuberculosis, D. Streptococcus mutans", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]