Answer:
B) gallons per hour
Step-by-step explanation:
The pool volume is measured in gallons, so that is the appropriate unit for use in the rate. The time will likely be measured in hours (not minutes or seconds), so that, too, is the appropriate unit for the rate.
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<em>Comment on other units</em>
If the pool is filled from a fire hose or other high-volume source of water (irrigation pump, for example), the appropriate units may be gallons per minute. (It might only take 10 to 20 minutes.)
In a metric country, the appropriate units might be liters per minute or hour, or cubic meters per minute or hour. (The pool volume is about 83.3 m³.)
For the problem here, the unit of cups is way too small to be of interest, and (large volume) flow rates are rarely expressed in cups per unit time.
