Fact 1: Nuclear reactions in stars causes stars to produce light.

Fact 2: Nuclear reactions convert mass to energy.

Given the two facts above, answer the question "what causes stars to produce light?" with the following options: 
- by making heat
 - Generating heat
 - converting mass to energy
 - photosyntehsis
 - photosynthetic pigments?
 - Evaporation of water
 - heat production
 - hydrogen and oxygen


 

   converting mass to energy      