Tony plans to run a 5,000-meter fun run at a constant rate of 250 meters per minute. He uses function f to model his distance from the finish line x minutes after the start of the race.

x f(x)
0 5,000
1 4,750
2 4,500
3 4,250
4 4,000
5 3,750
6 3,500


A.
Tony's function is always decreasing.
B.
Tony's function is always negative.
C.
Tony's function is exponential.
D.
The domain of Tony's function is [0 , 5,000].