what is the reason for the emission of light after the gas in a discharge tube is excited?\na photo…

Brief Explanations:

When gas in a discharge - tube is excited, electrons in the gas atoms gain energy and jump to higher energy levels. When these electrons return to lower energy levels, they emit light. Photo - electric emission is related to the emission of electrons from a surface when light shines on it. Spontaneous radioactive reaction involves the decay of unstable nuclei. High - energy reaction of the gas inside the tube is a very general and not the specific reason for light emission here.

Answer:

C. energy jumps by electrons due to excitation