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': "Koebner's phenomenon is characteristic of \nSelect and explain. \nA. Psoriasis, B. Pemphigus vulgaris, C. Pityriasis rosea, D. Lupus vulgaris", 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Psoriasis', 'role': 'assistant'}]