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
The mechanism of action of psoralen is: 
Select and explain. 
A. Binding to DNA, B. Inhibiting protein synthesis, C. Inhibiting angiogenesis, D. Inhibiting keratinization
A: Binding to DNA
Answer: A: Binding to DNA 
Explanation: A. i.e. Binding to DNA