What is a numbering plan?

A.
It describes the path from one endpoint to another.

B.
It describes the calling privileges of an endpoint.

C.
It describes how digits are manipulated in processing a call.

D.
It describes call coverage in a dial plan.

E.
It describes the endpoint addressing used in a voice system.

Explanation:
A numbering plan is a world-wide standard to organize and locate telephones all around the world.
In CCNA Voice, you often read about E.164 standard.