C. They both have the same slope.
To determine the slope of f(x), we divide 400 by 50 to determine how fast Xavier runs per second, which is the rate of change
So slope of f(x) = 400/50 = 8
For g(x), the slope can be determined by using two given points from the table and plugging them into the formula (y2-y1)/(x2-x1)
So if we plug in the first two points, we get
(12+4)/(5-3) = 16/2 = 8
Slope of f(x) = 8
Slope of g(x) = 8