Which of the Following Is an Example of Price Discrimination

Which of the following is an example of price discrimination?

A) Both Andy and Beth pay $7 for a ticket to the same movie,although the show timings are different.
B) Ann purchases a coach ticket on an airline for $250 while Bill purchases a first class ticket on the same flight for $900.
C) Aaron purchases a hardback copy of Harry Potter and the Deathly Hallows for $25 while Barbara waits and purchases a copy of the same book six months later for $8.
D) Audrey buys a front-row seat at a concert with back-stage access for $1,200,while Ben pays $500 for seats further away from the stage.