Answer: D. $98$

Explanation:

$1$ . Understand the relationship between a function and its graph's slope:

   - The given function is $f(x) = 98x$ . The graph is represented by the equation $y = 98x$.

   - This equation is in the slope-intercept form, $y = mx + b$ , where m is the slope and b is the y-intercept.

$2$ . Identify the slope (m) from the equation:

   - In the equation $y = 98x$ , the coefficient of x is $98$, and the y-intercept b is $0$.

   - Therefore, the slope m is $98$ .

$3$ . Conclusion:

   - The slope of the graph of $y = f(x)$ is $98$, which corresponds to option D.