Geoff Is Willing to Pay $13 for a Sixth Entrance

Geoff is willing to pay $13 for a sixth entrance to a mountain bike park. The market price for entrance is $10.50. The bike park is willing to accept $8.75. The total economic surplus generated from Geoff's sixth trip to the bike park is

A) $4.25.
B) $1.75.
C) $10.50.
D) $2.50.
E) $13.00.