Janelle flies her kite several feet in the air. She then reels the kite in at a constant number of feet per minute. The equation y=-18+ 240 represents this situation, where x is the number of minutes and y is the height of the kite in the air. What does the number -18 in the equation represent? A. The kite is 18 feet above the ground before Janelle starts reeling it in.

B. The kite ascends 18 feet per minute.

C. The kite descends 18 feet per minute.

D. The kite is 18 feet above the ground after Janelle is done reeling it in.