Sunsets Are Red Because

Sunsets are red because

A) the Sun emits more red light when it's setting.
B) sunlight must pass through more atmosphere, and this scatters even more light at bluer wavelengths, transmitting mostly red light.
C) sunlight must pass through more atmosphere, and this scatters more light at red wavelengths than bluer wavelengths.
D) the cooler atmosphere in the evening absorbs more blue light.
E) none of the above