Gamma Rays Are Generally Absorbed in Earth's Atmosphere

Gamma rays are generally absorbed in Earth's atmosphere. However, it is possible to build Earth-based observatories that detect secondary effects of gamma rays, such as the blue light produced when the particles they collide with move faster than the speed of light in air. This blue light is called

A) synchrotron light.
B) Cherenkov light.
C) ultraviolet light.
D) superluminal light.