Khalil Is Offered a Free Ticket to the Opera,which He

Multiple Choice

Khalil is offered a free ticket to the opera,which he cannot resell.His opportunity cost of going to the opera is:

A) zero-the tickets were free.
B) the price listed on the ticket.
C) whatever Khalil would have done had he not gone to the opera.
D) the price listed on the ticket and whatever Khalil would have done had he not gone to the opera.