Answer:
B. 5 gallons per minute.
Explanation:
The tub is being filled when the volume is increasing. That is, at the point where the graph has a positive slope.
To find the rate at which the tub is being filled, pick two points from the part of the graph marked with red above.
They are: (4,20) and (0,0).
Next, find the rate of change.
![\text{Rate of change=}(20-0)/(4-0)=(20)/(4)=5\text{ gallons per minute}](https://img.qammunity.org/2023/formulas/mathematics/college/61ewv74bz6r0kttjnvb9uq79f7wrvezoil.png)
The tub is being filled at a rate of 5 gallons per minute.