What Is a Domain Name System (DNS)

What is a domain name system (DNS) ?

A) allows dynamic IP address allocation so users do not have to have a preconfigured IP address to use the network
B) converts IP addresses into domains, or identifying labels that use a variety of recognizable naming conventions
C) the efficient coexistence of telephone, video, and data communication within a single network, offering convenience and flexibility not possible with separate infrastructures
D) the integration of communication channels into a single service