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
Psoralen + ultraviolet light (PUVA) therapy is useful in the treatment of: 
Select and explain. 
A. Psoriasis, B. Vitiligo, C. Mycosis fungoides, D. All
D: All
Answer: D: All 
Explanation: D. i.e. All