You Have Rented Your First Apartment,signing a Lease That Commits

You have rented your first apartment,signing a lease that commits you to pay $500 each month for 12 months.You have an opportunity to take a trip to Europe during the entire month of June,and you will spend $2 000 travelling.Your apartment will be vacant,but because of your lease,you must still pay the rent.The cost of taking the trip to Europe is:

A) $2 000 because the $500 for your June rent is a sunk cost.
B) $2 500 because this is your total spending during the month of June.
C) $1 500 because the June rent is an opportunity cost of travelling that must be deducted from the explicit cost of the trip.
D) $2 500 because the June rent is an opportunity cost of travelling and must be added to the explicit cost of the trip.