Which of the following is the most appropriate unit to describe the rate at which water flows out through a standard household faucet?
1) Minutes per gallon, because the independent quantity is volume of water in gallons and dependent quantity is time in minutes
2) Minutes per gallon, because the independent quantity is time in minutes and dependent quantity is volume of water in gallons
3) Gallons per minute, because the independent quantity is volume of water in gallons and dependent quantity is time in minutes
4) Gallons per minute, because the independent quantity is time in minutes and dependent quantity is volume of water in gallons