What functions do tables in a relational database serve?

Tables in a relational database play a crucial role in organizing and storing data in a structured format. The primary function of tables is to contain related sets of data, which allows for logical data organization that facilitates efficient retrieval, manipulation, and management of that data.

Each table is made up of rows and columns, where rows represent individual records or entries, and columns represent the attributes of those records. This organization allows users to establish relationships between different sets of data through foreign keys and primary keys, enabling complex queries and data operations.

In a relational database, the ability to relate data across different tables is essential for maintaining data integrity and for performing operations like joins, which combine data from multiple tables based on shared attributes. Thus, the true essence of a relational database is its capacity to hold collections of related data within these tables, making option D the correct choice.