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': "Which of the following test is likely to helpful in diagnosing a patient presenting with an itchy annular plaque on the face? \nSelect and explain. \nA. Gram's stain, B. Tissue smear, C. Wood's lamp examination, D. Potassium hydroxide mount", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Patient in the question is most likely a case of fungal infection of the skin of the face. So the best method to diagnose the condition would be a KOH mount, in which the keratin of the skin will be lysed and the fungal hyphae and other elements are clearly visualised. KOH mount in a case of Tinea corporis will show "Spaghetti and meatballs" appearance. Ref: Laboratory Diagnosis of Infectious Diseases: Essentials of Diagnostic Microbiology By Paul G. Engelkirk, Page 491; Combating Fungal Infections: Problems and Remedy By Iqbal Ahmad, Pages 179-80.', 'role': 'assistant'}]