The correct option is B shorter wavelengths
Sunlight consists of seven colours. Of these, red has the maximum wavelength. During sunrise and sunset, the rays have to travel a larger part of the atmosphere because they are very close to the horizon. Lights with shorter wavelength are scattered first than with larger wavelength.
Therefore, light other than red having shorter wavelengths is mostly scattered away. Most of the red light, which is the least scattered, enters our eyes. Hence, the sun and the sky appear red.