What is a virtual table?

What is a virtual table?

A.
A virtual table is a relation created as the result of data manipulation; it exists only in computer memory, and is not a permanent part of the database.

B.
A virtual table is a relation stored in the database; it is used when multiple users access the same relation in a database.

C.
A virtual table is a relation derived from the database data dictionary; it contains metadata about a base relation. A virtual table is a relation derived from the database?data dictionary; it contains metadata about a base relation.

D.
A virtual table is a relation that consists of primary and foreign keys for a particular set of relations in a database.