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': 'Collarette of scales is a feature of: \nSelect and explain. \nA. Acne, B. Psoriasis, C. Pityriasis rosacea, D. Pemphigus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Pityriasis rosacea', 'role': 'assistant'}]