Answer: Rectangle
Step-by-step explanation: When a plane intersects a cone, the resulting shape can vary depending on the angle and position of the intersecting plane. However, the intersection of a cone and a plane will never produce a rectangle.
Here are the possible shapes that can be formed by the intersection of a cone and a plane:
1. Circle: If the intersecting plane is perpendicular to the axis of the cone, the intersection will be a circle.
2. Ellipse: If the intersecting plane is slanted and cuts through the cone, the resulting shape will be an ellipse.
3. Parabola: If the intersecting plane is parallel to one of the cones' sides, the intersection will be a parabola.
Therefore, the shape that cannot be the intersection of a cone and a plane is a rectangle.