Which is not a characteristic of a regular polyhedron?

a. it is also considered to be a convex polyhedron.
b. the number of edges meeting at each vertex is the same for all vertices.
c. all of the faces are congruent.
d. it is not a platonic solid.

The best and most correct answer among the choices provided by your question is the first choice or letter A. A polyhedron is not considered as a convex polyhedron.

A polyhedron is said to be convex if its surface (comprising its faces, edges and vertices) does not intersect itself and the line segment joining any two points of the polyhedron is contained in the interior or surface. 

I hope my answer has come to your help. Thank you for posting your question here in

Documentation and time management