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': 'The microscope used in microbiology - \nSelect and explain. \nA. Light microscope, B. Phase contrast microscope, C. Fluorescent microscope, D. All', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Why is it necessary to use a microscope in microbiology?\nThe diameter of the smallest object that can be seen by the naked (unaided) eye is about 200U.\nMost microorganisms are smaller than this and therefore, they should be sufficiently magnified before study.\nFor this purpose various types of microscopes are available.\nTypes of microscopes \nA) Visible light as a source of illumination\n\nBright-field microscope, commonly known as a light microscope or optical microscope.\nDarkfield microscope\nPhase contrast microscope\n\nB) UV rays as a source of illumination\n\nFluorescence microscope\n\nC) Electron beam forms image of specimen\n\nElectron microscope\n\nD) Surface forces form image of specimen\n\nAtomic force microscope (AFM)', 'role': 'assistant'}]