You Paid $35 for a Ticket (Which Is Non-Refundable)to See

You paid $35 for a ticket (which is non-refundable) to see SPAM, a local rock band, in concert on Saturday. Assume that $35 is the most you would have been willing to pay for a ticket. Your boss called, and she is looking for someone to cover a shift on Saturday at the same time as the concert. You would have to work 4 hours and she would pay you $11/hr. The psychic cost to you of working is $2/hr. What is your opportunity cost of going to work on Saturday?

A) $0
B) $9
C) $35
D) $36