Final answer:
The rate at which the water level rises is decreasing when considering a container with a non-uniform cross-section, as each increment of volume will result in lesser increments of water level as the container widens. Option b is the correct answer.
Step-by-step explanation:
When considering the scenario where the rate of change of the volume of water is constant, it implies that the water volume is increasing at a uniform rate over time. Now, the way the water level rises in a container as the volume of water increases will depend on the shape of the container.
If the container has uniform cross-sectional area, such as a cylindrical container, the height of the water (which is the water level) will also increase at a constant rate since the same volume change will result in the same height change regardless of the water level. However, if the container's cross-sectional area expands with height (like a cone or a bowl), the rate at which the water level rises will decrease as the volume increases, because the same volume increment will occupy a larger area and thus result in a smaller rise in level.
The correct option that relates to the rate at which water level rises when the change in volume is constant is therefore option (B): The rate at which the water level rises is decreasing.