I'm unable to see the image you mentioned. However, if the graph shows a line representing the water level of the tank over time, the x-axis typically represents the time in hours and the y-axis represents the gallons of water.
To determine how long it will take for the tank to be emptied, you should look for the point where the line intersects the x-axis (y = 0). The x-value at this point will give you the time it takes to empty the tank.
Based on the options provided, if the graph indicates that the water level reaches 0 gallons around 12 hours, then the correct answer would be 12 hours. If it indicates a different value such as 11.7 hours, then that would be the answer.
Without the visual reference of the graph, it's impossible to determine the exact answer. Please check the graph carefully for the x-axis crossing point.