What does the concept of referential integrity ensure?

The concept of referential integrity plays a crucial role in relational databases by ensuring that relationships between tables are consistent and valid. It enforces rules that maintain the accuracy and reliability of data across tables. For example, if a foreign key in one table references a primary key in another table, referential integrity ensures that every value of the foreign key must match a corresponding value in the primary key of the relevant table. This prevents orphan records and maintains meaningful relationships, thus safeguarding the database's structural integrity.

In contrast, the other options do not align with the essence of referential integrity. Independence of tables would lead to a lack of meaningful relationships, undermining the relational model's purpose. Storing data in a time series format is unrelated to referential integrity, focusing instead on how data is organized rather than how tables relate to one another. Lastly, uniformity of data types across tables is important for the functionality of a database but isn't the central aim of referential integrity, which focuses specifically on the validity of relationships between data in different tables.