The graph shows the number of gallons remaining in a pool, y after x hours.

What characteristic is true of the function?
The pool is empty after 16 hours. The rate of change is 1,000 gallons per hour.
The pool is empty after 16 hours. The rate of change is negative 1 comma 000 gallons per hour.
The pool is full after 16 hours. The rate of change is 1,000 gallons per hour.
The pool is full after 16 hours. The rate of change is negative 1 comma 000 gallons per hour.