The correct answer is C. DDL.
Data Definition Language (DDL) is a set of commands used to define the structure of a database. It is used to create, alter, and drop database objects such as tables, views, and indexes.
Data Manipulation Language (DML) is a set of commands used to manipulate data in a database. It is used to insert, update, and delete data from tables.
Data Control Language (DCL) is a set of commands used to control access to data in a database. It is used to grant and revoke permissions on database objects.
DDL is the only language that is concerned with the definition of the whole database structure and schema. DML and DCL are concerned with the manipulation and control of data, respectively.