This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'The bacteria frequently used as an immunomodulator is \nSelect and explain. \nA. Corynebacterium parvum, B. Mycobacterium marinum, C. Chromobacterium violasium, D. Flavobacterium meningosepticum', 'role': 'user'}, {'content': "Answer: A \nExplanation: Corynebacterium parvum, which is frequently used as an immunomodulator, is a mixture of the Propionibacterium species. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 246", 'role': 'assistant'}]