Assume that in October you bought a $450 nonrefundable airline ticket to Telluride, Colorado, for a 5-day/4-night winter ski vacation. You now have an opportunity to buy an airline ticket for a 5-day/4-night winter ski vacation in Stowe, Vermont, for $400 that includes a free ski lift ticket. The price of your lift ticket for the Telluride vacation would be $300. The price of a hotel room in Telluride is $180 per night.

The price of a hotel room in Stowe is $150 per night. Which of the following costs is not relevant in a decision of whether to proceed with the planned trip to Telluride or to change to a trip to Stowe?

a. The $450 airline ticket to Telluride.

b. The $400 airline ticket to Stowe.

c. The $300 lift ticket for the Telluride vacation.

d. The $180 per night hotel room in Telluride.