You go to the movie theater to see the latest release by your favorite actor. You quickly realize the movie is not very good, but instead of walking out, you stay to watch the rest of the movie, figuring that you've already spent $9.50 for a movie ticket and $6 for popcorn. This is an example of the _______ bias.
a. anchoring and adjustmentb. representativec. sunk-costd. confirmation