The ultraviolet spectrum can be divided into three regions based on wavelength: UV-A (315–400 nm), UV-B (280–315 nm), and UV-C (100–280 nm). 

(a) Photons from which region have the highest energy and therefore are the most harmful to living tissue? 

(b) In the absence of ozone, which of these three regions, if any, are absorbed by the atmosphere? 

(c) When appropriate concentrations of ozone are present in the stratosphere, is all of the UV light absorbed before reaching the Earth’s surface? If not, which region or regions are not filtered out?