The volume of water, in gallons, remaining in a tank as it drains can be modeled by the function , where is the volume of water and is the time in minutes since draining began. Which of the following statements is the best interpretation of the number 120 in this context?
The initial volume of water in the tank.
The total time it takes for the tank to drain completely.
The rate at which water is draining from the tank, in gallons per minute.
The volume of water remaining after 120 minutes.
