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
Wavelength of UVB rays is ? 
Select and explain. 
A. 290 - 320 nm, B. 320 - 360 nm, C. 360 - 390 nm, D. 390 - 420 nm
A: 290 - 320 nm
Answer: A: 290 - 320 nm 
Explanation: Ans. is 'a' i.e., 290 - 320 nm UV rays are used directly to treat skin conditions. It is simply referred to as phototherapy. These may be :? UVB phototherapy (290-320 nm) Narrow band UVB phototherapy (311 nm) UVA1 phototherapy (360-380 nm)