D is corrent because data definition language is used to define a database, including creating, altering, and deleting tables and establishing various constraints. A is incorrect because data manipulation language is composed of commands used to maintain and query a database, including updating, inserting in , modifying and querying (asking for data). B is incorrect because the term data query language is not used in information technology. C is incorrect because data control language is composed of commands used to control a database, including controlling which users have various privileges (e.g., who is able to read from and write to various portions of the database).
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