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': 'The mechanism of action of psoralen is: \nSelect and explain. \nA. Binding to DNA, B. Inhibiting protein synthesis, C. Inhibiting angiogenesis, D. Inhibiting keratinization', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A. i.e. Binding to DNA', 'role': 'assistant'}]