Answer
$\text{(a)}$ $m=0$, $b=4$.
$\text{(b)}$ Refer to the graph below..
$\text{(c)}$ $0$.
$\text{(d)}$ constant.
Work Step by Step
Given $F(x)=4$, we have:
$\text{(a)}$ Compare with the slope-intercept form $y=mx+b$, we can determine the slope as $m=0$ and $y$-intercept as $b=4$.
$\text{(b)}$ Start from $(0,4)$. With a slope of $0$, move $1$ unit right, then stay to reach $(1,4)$. Complete the graph by connecting the two points using a straight line. Refer to the graph below.
$\text{(c)}$ The average rate of change $R$ is the slope in this case, thus $R=m=0$.
$\text{(d)}$ We can see that the linear function is a constant.