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': 'Diene method is used for \nSelect and explain. \nA. Mycoplasma, B. Chlamydia, C. Plague, D. Diphtheria', 'role': 'user'}, {'content': "Answer: A \nExplanation: Mycoplasma colonies may be seen with a hand lens but are best studied after staining by the Dienes method. For this, a block of agar containing the colony is cut and placed on a slide. It is covered with a coverslip on which an alcoholic solution of methylene blue and azure has been dried. Ref: Textbook of microbiology; Ananthanarayan paniker's; 10th edition; Pg:394", 'role': 'assistant'}]