Ray optics

At sunset or sunrise the suns rays have to pass through a larger distance in the atmosphere and most of the blue and other shorter wavelengths are remove by scattering.

Correct answer is (b) sun's rays have to pass through a larger distance in the atmosphere Rayleigh scattering is proportional to (1/lamda)^4 Most of the blue and other shorter wavelengths are removed by scattering because have less wavelength greater refractive index greater angle of deviation