Ingrid Has Been Waiting for the Show "Mamma Mia!" to Come

Ingrid has been waiting for the show "Mamma Mia!" to come to town. When it finally does come, tickets cost $60. Ingrid's reservation price is $75. But when Ingrid tries to buy a ticket, they are sold out. Suppose Steven was able to purchase a ticket at the box office for $60. Steven's reservation price for the ticket is $65. If Steven attends "Mamma Mia!" and Ingrid does not, then this situation is:

A) inefficient because Steven and Ingrid could have made a mutually beneficial trade.
B) efficient because Steven paid less for the ticket than his reservation price.
C) efficient because Steven arrived at the ticket counter before the show was sold out.
D) inefficient because Ingrid would have enjoyed the show too.