Answer
The average rate of change of function $f$ will always remain constant.
The average rate of change of function $g$ will increase as it moves on to the next successive interval.
The average rate of change of function $h$ will decrease as it moves on to the next successive interval.
Work Step by Step
Since the slope of function $f$ will always be the same, so will the average rate of change.
Since the slope of function $g$ is increasing as the $x$ value gets higher, so will the average rate of change.
Since the slope of function $h$ is decreasing as the $x$ value gets higher, so will the average rate of change.