Answer:
The cereal box has three pairs of parallel planes.
Explanation:
A cereal box (cuboid) has six planes denoting each of its faces.
Each of the planes/faces in the cereal box is parallel to one other plane/face in the box which lies opposite to it.
For example let us consider the following nomenclature for the faces of the box when it is kept on ground:
Face F1 denotes the face at the top
Face F2 and F3 are adjacent to F1 on either side between the top and bottom faces.
Face F4 represents the bottom face.
Faces F5 and F6 are the two remaining faces of the box opposite to each other. Now in this scenario, we have the following 3 pairs of parallel planes:
F1,F4
F2,F3
F5,F6