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: Dental
Best range of UV light used for treatment of skin diseases 
Select and explain. 
A. 100 – 200 nm, B. 200 – 400 nm, C. 400 – 700 nm, D. > 700 nm
B: 200 – 400 nm
Answer: B: 200 – 400 nm 
Explanation: UV light most commonly used in dermatology are UVB (290 - 320 mn), narrow band UVB (311 nm), and UVAi (360 - 380 nm).