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': "True about diptheria is - \nSelect and explain. \nA. Loffler's serum is highly selective medium for C. diptheria, B. Elek's Gel is a precipitation test, C. Metachromatic granules is produced on stain only by one strain of C. diphtheria, D. Gm -ve bacilli, non motile, non capsulated", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]