The following table shows the number of feet a bird flies above the ground as a function of time:
time (in seconds) x distance above ground (in feet) f(x)
0 21
2 18
4 15
6 12
8 9

find and interpret the meaning of the x-intercept in this scenario.
a. (21, 0); the time it takes for the bird to reach the ground
b.(14, 0); the time it takes the bird to reach its highest point
c. (21, 0); the time it takes the bird to reach its highest point
d. (14, 0); the time it takes for the bird to reach the ground