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

Fact 2: Light contains energy.

Given the two facts above, answer the question "What do nuclear reactions in stars cause?" with the following options: 
- heat energy
 - Change colors
 - production of energy
 - hydrogen and oxygen
 - only black holes
 - destruction of energy
 - creation of life
 - harmful substances


 

   production of energy      