I need help! Quickly, please!

The water level during a long drought fell 7 1/2 feet one year and fell another 5 1/4 feet the next year. What was the total change in the water level for those two years?
A. -12 3/4 ft.
B. 2 1/4 ft.
C. 12 3/4 ft.
D. -2 1/4 ft.