3. Sunk costs and decision making

Eric has plans to go to a play and already has a $50 nonrefundable, nonexchangeable, and nontransferable ticket. Now Ginny, whom Eric has wanted to date for a long time, asks him to a concert. Eric would prefer to go to the concert with Ginny and forgo the play, but he doesn't want to waste the $50 he spent on the play ticket.

From the perspective of an economist, if Eric decides to go to the play, what has he just done?

Made an optimal choice

Incorrectly allowed a sunk cost to influence his decision

Correctly ignored a sunk cost