What does 'data integrity' ensure in a database system?

Data integrity primarily ensures the accuracy and reliability of data within a database system. This concept is fundamental because it guarantees that data is stored correctly and remains uncorrupted throughout its lifecycle.

Achieving data integrity involves several practices, such as validating inputs, using constraints to enforce rules (like unique keys or foreign keys), and implementing appropriate data types. When data integrity is preserved, organizations can trust the information held in their databases for decision-making, reporting, and other business functions.

In contrast, the other options focus on different aspects of database management. Access control pertains to security measures that regulate who can view or manipulate data, data redundancy deals with the unnecessary duplication of data, and the speed of data retrieval relates to the efficiency of accessing data rather than its correctness. Each of these components plays a role in a comprehensive database management system but does not define the core principle of data integrity.