Which of the following is an example of non-polyhedron?
The correct option is D Cone
Polyhedron is a 3 dimensional shape having polygons as faces joined by sides.
Cube, triangular prism and triangular pyramid are 3 dimensional figures having polygons as faces joined by sides.
Cone is a 3 dimensional figure. But its is not not made up of polygons. Hence, cone is a non-polyhedron.