As a 7- Year- Old Child, You Helped Your Father

As a 7- year- old child, you helped your father nail a birdhouse 7 feet high on a 10- foot- tall maple tree. If the tree grew an average of 12 inches per year, except during a dry year when it grew only 2 inches, how high in the tree is the birdhouse when you are 18 years old?

A) 17 feet, 2 inches
B) 10 feet
C) 7 feet
D) 17 feet
E) 19 feet