Which of these situations does not have quantities that combine to make 0?

O A. A dolphin swims 20 feet straight down from the surface. It then
rises 20 feet to return to the surface.

B. A hot air balloon rises 40 feet. It then drops 40 feet to the ground.

C. Hiroko earns $20 working concessions at the football game. She
then earns $20 as a babysitter.

D. In the morning, the temperature rises 30 degrees. In the evening, it
falls by 30 degrees.