Identify the graph that displays the depth of water in a swimming pool after the drain is opened. a. A graph has time on the x-axis and depth on the y-axis. A line has a positive slope. c. A graph has time on the x-axis and depth on the y-axis. A line decreases, increases, and then decreases to the x-axis. b. A graph has time on the x-axis and depth on the y-axis. A line has a negative slope. d. A graph has time on the x-axis and depth on the y-axis. A line is constant at a point, and then is vertical to the x-axis.