To find the slope of the linear graph with the given points (2, 20) and (6, 44), we can use the slope formula:
\[ \text{slope} = \frac{y_2 - y_1}{x_2 - x_1} \]
Here, \((x_1, y_1) = (2, 20)\) and \((x_2, y_2) = (6, 44)\).
Plugging in the values:
\[ \text{slope} = \frac{44 - 20}{6 - 2} = \frac{24}{4} = 6 \]
So, the slope is 6, which means that the parking fee rises by $6 for each additional hour of parking.
Therefore, the correct interpretation of the slope as the rate of change in the parking fee for each additional hour of parking is:
The parking fee rises by $6 with each additional hour.