When examining solids, the shape of the cross section taken parallel to the base can vary depending on the type of solid. If we consider common solids like a cylinder, prism, or a rectangular solid, the cross sections taken parallel to the base will be rectangular. However, if we look at a cone, it presents a different scenario.
A cone has a circular base, and when you take a cross section parallel to this circular base (but above it), the resulting shape is also circular rather than rectangular. Therefore, the answer to the question is that a cone, when sliced parallel to its base, provides a cross section that is not a rectangle.