Which type of integrity constraint focuses on fundamental information-based constraints?

The type of integrity constraint that focuses on fundamental information-based constraints is the relational integrity constraint. Relational integrity constraints are designed to maintain the accuracy and consistency of data within a relational database. They enforce rules that preserve the relationships between different entities in the database, ensuring that the data adheres to the principles of relational theory.

For example, relational integrity constraints include primary keys, foreign keys, and unique constraints that help maintain data relationships. These constraints are essential for maintaining the integrity of relational databases because they prevent operations that would lead to data inconsistency, such as orphan records or duplicate entries.

In contrast, the other options represent different types of constraints that, while important, do not specifically focus on the fundamental relationships and structures defined within relational databases. Business critical integrity constraints may relate to organizational requirements but are more about operational needs than foundational data principles. Data integrity constraints cover a broader spectrum that includes relational constraints but also encompasses others such as domain constraints, which are specific to the permissible values for a given attribute. Static information constraints might refer to fixed rules applying to data without considering its relational structures. Hence, relational integrity constraints are identified as the most relevant in maintaining foundational integrity in information systems.