Answer
d) Emission of photons of visible light is the correct answer
Work Step by Step
The Violent eruptions on the surface of the sun (solar flares) cause ejection of the electrons and protons into space, and they disturb several transmission and gives us with the celestial light called as auroras The electrons and protons collide with the atoms and molecules in the atmosphere of the earth's upper layer, they become ionized and electronically excited. then, the excited molecules and ions return to the ground state with the emission of light and gives rise to the aurora borealis and the aurora Australis.
so the main cause is the emission of the photon of the light which is visible to us.
