Algebra-1

Question Analysis
This question tests the student’s ability to apply the concept of zero slope to a more advanced real-world scenario. Although water is flowing into and out of the tank, the water level remains constant over time, which corresponds to a horizontal line on a graph with a slope of zero.

Key Concept Explanation
In a graph where the y-axis represents the water level and the x-axis represents time, a horizontal line indicates that the water level does not change as time passes. When the rate of water flowing in equals the rate flowing out, there is no net change in the water level, resulting in a slope of zero.

Step-by-step Solution
1. Identify the scenario: Water flows into and out of the tank at the same constant rate, so the water level ...