Answer: Choice B) real numbers from 0 to 6 (including 0; including 6)
The domain is the set of allowed x values to be inputs of the function. The x axis is the horizontal axis. The graph starts at x = 0 as the smallest x value, which is the left-most x value. The largest x can get is x = 6 which is the right-most x value. The value of x can be anything in between 0 and 6, including the endpoints. This graph basically shows that the pond is fully drained in 6 minutes.