While Steve Is Cleaning Out His Garage, He Finds an Old

While Steve is cleaning out his garage, he finds an old surfboard that he no longer needs. As he walks to the dumpster to throw it out, his neighbor John asks if he could have it. John offers Steve a 6-pack of beer (worth $10) in exchange, which Steve happily accepts. Steve has achieved a producer surplus of:

A) $0, since he was just going to throw out the board.
B) $10, the value of the beer he received.
C) $5, because Steve and John benefited equally from the $10 transaction.
D) $50, because that's what the surfboard was likely worth.