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': 'Scratch sign is positive in \nSelect and explain. \nA. Tinea capitis, B. Tinea unguium, C. Tinea versicolor, D. Tinea mannum', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Scratch sign is present in Tinea versicolor, where firmly scratching the skin makes the scales visible.', 'role': 'assistant'}]