Psychology question explain cognitive dissonance and three ways it can be relieved.

Cognitive dissonance, is a term used in psychology that explains the feeling of discomfort by a person who is facing two situations that contradict each other.  

An example used to explain it, is the story of the fox who very much wants to eat a bunch of grapes that is in a very high place. As the Fox can not find a way to reach it, she gives up using the excuse that the grapes are green and bitter.

To alleviate cognitive dissonance, one can:

1- Change the behavior to relieve the situation of discomfort.

2- Try to justify the discomfort with new ideas

3- Justify the discomfort.