Which of the Following Is an Example of Cognitive Dissonance

Which of the following is an example of cognitive dissonance?

A) As a teenager,you vowed to wait until marriage before having sex.Now,as an unmarried adult you have sex with your romantic partner and believe that sex outside of marriage is okay,as long as it is with someone you love.
B) Over time you have come to realize that your parents are not always right.
C) While you used to dislike your boss,over the past few years you have actually grown to like her.
D) You rarely speak to the person who was once your best friend.