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: Pathology
[{'content': 'Psoralane Ultra Violet A (PUVA) therapy is advised in \nSelect and explain. \nA. Pemphigus vulgaris, B. Apthous ulcers, C. Carcinoma in situ, D. ANUG', 'role': 'user'}, {'content': 'Answer: A \nExplanation: According to Rook and Colleagues the extra corporeal photochernotherapy for drug resistant pemphigus vulgaris include administration of 8-methoxypsoralen followed by exposure of peripheral blood to ultraviolet radiation. It is also used for vitiligo and graft versus host disease.', 'role': 'assistant'}]