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: Skin
[{'content': 'A 24 year old man presented with multiple small hypopigmented macules around hair follicles on upper chest and back. Scratching of the lesion with a glass slide showed fine scaling. Which of the following is the investigation of choice in diagnosing this condition? \nSelect and explain. \nA. KOH preparation of scales, B. Tzank test, C. Slit Skin Smear Examination, D. Skin biopsy of lesion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Patient is showing features of Pityriasis Versicolor caused by Malassezia furfur. Lesions appear as hypopigmented, scaly, perifollicular macules which coalesce together. It is diagnosed using KOH mount of the lesion which shows a mixture of sho branched hyphae and spores (spaghetti and meat ball appearance). Ref: Illustrated Synopsis of Dermatology and Sexually Transmitted Diseases By Neena Khanna 2ND edn page 245.', 'role': 'assistant'}]