what is denoted by a `zone’?

When referring to the Domain Name Service, what is denoted by a `zone’?

A.
It is the first domain that belongs to a company.

B.
It is a collection of resource records.

C.
It is the first resource record type in the SOA.

D.
It is a collection of domains.

Explanation:
A reasonable definition of a zone would be a portion of the DNS namespace where responsibility has been delegated.