This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
[{'content': 'Psoralen-A is used in the treatment of: \nSelect and explain. \nA. Pemphigus, B. Vitiligo, C. Pityriasis alba, D. Icthyosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Photochemotherapy (PUVA: Psoralen ultraviolet A)- Photoactivated psoralen undergoes 02 independent as well as 02 dependent reactions and binds to pyrimidine bases- interferes with DNA synthesis and epithelial cell turnover. Oral methoxsalen is followed 1-2 hours later by UVA exposure on alternate days. ESSENTIALS of medical PHARMACOLOGY SEVENTH EDITION-KD TRIPATHI page:892', 'role': 'assistant'}]