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': 'Hair perforation test is positive in infection with - \nSelect and explain. \nA. Trichophyton, B. Microsporum, C. Epidermophyton, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Hair perforation test\n\nThe hair perforation test consists of inoculating colonies of an organism into a dish containing a small amount of water, a few drops of yeast extract solution and some human hair. The dish is incubated at 300C and after 7 days, some of the hair is taken and are kept on a slide with a coverslip and are observed under a microscope. The test is considered positive if the hair has a deep, narrow wedge-shaped perforation in it.\nHair perforation test is done to distinguish between isolates of dermatophytes, particularly trichophyton mentagrophytes and its variants.', 'role': 'assistant'}]