The temperature was 80°F and then fell 20°F . Which number line diagram could be used to represent this situation?
A. A number line diagram with an arrow that starts at 80 , is 20 units long, and points to the right.
B. A number line diagram with an arrow that starts at -20 , is 80 units long, and points to the right.
C. A number line diagram with an arrow that starts at -20 , is 80 units long, and points to the left.
D. A number line diagram with an arrow that starts at 80 , is 20 units long, and points to the left.