Greg plays trombone in his school band during football games. During a rally song in the stands on day. Greg annoys one of the opposing team's fans, who grabs his $400 trombone and hurls it down the bleachers, completely destroying it. Greg's insurance pays him $400 to replace the trombone, but then the opposing team's coach also offers to replace the instrument, at whatever the cost. So Greg orders a new 3,200 trombone and has the opposing team's athletic department absorb the cost. Which principle has Greg violated?
Select one of the following: