If You Receive $18 Worth of Pleasure from the First

If you receive $18 worth of pleasure from the first hole of golf played and your additional pleasure from succeeding holes drops $1 for each hole played. You must pay $25 up front to get on the course but you can then play as many holes as you like for the day without any further charge. How many holes of golf will you play?

A) 9
B) 12
C) 18
D) As many holes as can be played from dawn until dusk.