Which of the following refers to commands that change data within a database?

The correct choice refers to commands that are specifically designed to alter, update, or manage data within a database. This set of commands is known as Data Manipulation Language (DML). Common operations performed by DML include inserting new records, updating existing ones, and deleting records from the database.

Data Definition, on the other hand, involves commands that define the structure of the database itself, such as creating or altering tables. Data Control pertains to permissions and access management within the database, focusing on controlling who has rights to the data and how it can be accessed. Data Retrieval, which deals with querying the database to fetch information, is separate from manipulating the data itself.

Thus, the focus on changing the data aligns perfectly with the term "Data Manipulation," which highlights its essential function in managing the actual data content housed within a database system.