I believe its D because the house and the ground is a 90 degree angle, and at 60 degree angle is a 20 foot ladder. alright then 90 plus 60 = 150 degrees.
then add the twenty foot ladder with each choice for the answer:
A: 20 + 6.1 = 26.1
B: 20 + 10.0 = 30
C: 20 + 14.1 = 34.1
D: 20 + 17.3 = 37.3
The answer would be D because it is the closer number to 150. Because it says " which is the closest height up the house the ladder reaches?" The answer is D the closest number. I HOPE THIS HELPS YOU! =D