The diagram illustrates the water cycle.
Parts of the water cycle labeled U through Z. U: Water moving from a lake into the clouds. V: Clouds. W: Water falling from clouds as rain and snow. X: Water moving from ground to the clouds. Y: Water flowing down the mountainside into a lake. Z: Underground water going into lake.
Which letter represents runoff?
A. U
B. W
C. X
D. Y
