Which of the following best describes the function of a database schema?

A database schema serves as a blueprint that outlines how database tables are organized, defining the structure of the data, the relationships between different tables, and the types of data that can be stored in each table. This includes details such as the columns in each table, their data types, constraints, and relationships with other tables, thereby providing a comprehensive framework for data management within the database.

While the other choices present related concepts, they do not accurately define the primary function of a database schema. For instance, the structure that contains the database files refers more to the physical storage aspect rather than how the data is organized logically. Similarly, methods for querying the database relate to how data is retrieved, not the organization's structure of that data, and security protocols pertain to access control rather than providing a framework for data arrangement. Thus, the definition that identifies the schema as a blueprint emphasizes its critical role in data organization and database design.