Answer:
The circle cannot be formed.
Explanation:
The polygons that are NOT formed when a cube is intersected by a plane would be : circle
A cube has only six plane faces, it is impossible that a plane can intersect a cube and create a cross section with a curved face. So a circle cannot be formed.
A square is formed when a cube is intersected by a plane parallel to its base.
A rectangle is formed when a cube is intersected by a plane in two pairs of opposite faces.
A triangle is formed when a cube is intersected by a plane in three adjacent faces.