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: Dental
[{'content': 'A24-year-old man had multiple, small hypopigmented macules on the upper chest and back for the last three months. The macules were circular, arranged around follicles and many had coalesced to form large sheets. The surface of the macules showed fine scaling. He had similar lesions one year age which subsided with treatment. The most appropriate investigation to confirm the diagnosis is – \nSelect and explain. \nA. Potassium hydroxide preparation of scales, B. Slit skin smear from discrete macules, C. Tzanck test, D. Skin biopsy of coalesced macules', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Information in this question are :-\n\n\nAdult patient (24 yrs)\nMultiple small hypopigmented macules\nOn chest and back\nMacules had started around follicle and then coalesced\nFine Scales\nRecurrent after treatment\n\n\nThe clinical diagnosis is P.versicolor which can be confirmed by examination of scales as wet mounts after treatment with 10% KOH.', 'role': 'assistant'}]