Van has plans to go to an opera and already has a $100 non refundable, non exchangeable, and non transferable ticket. Now Amy, whom Van has wanted to date for a long time, asks him to a party. Van would prefer to go to the party with Amy and forgo the opera, but he doesn't want to waste the $100 he spent on the opera ticket.

From the perspective of an economist, if Van decides to go to the party with Amy, what has he just done?

1. Incorrectly allowed a sunk cost to influence his decision

2. Made a choice that was not optimal

3. Correctly ignored a sunk cost