Explain why a three-dimensional figure with a curved surface is not a polyhedron.

We are given a '3-D figure with a curved surface'.

Now, we know that,

Which means that the faces of the polyhedron are 2-D closed shapes bounded by straight lines.

Since, the 3-D figure consists of curved surface and the polyhedron does not have any curved surface.

Thus, we have,

A three-dimensional figure with a curved surface is not a polyhedron.

the answer

b. they are parallel and will never intersect.