Which of the following is NOT a basic component of the relational model?

The correct answer is Option D. The relational model, as defined by E.F. Codd, fundamentally consists of three core components: relations (tables), tuples (rows representing records), and attributes (columns defining fields). These elements form the structural basis for organizing data in a relational database. While domains define valid values or data types for attributes, they are considered auxiliary concepts rather than a primary structural component in Codd's original framework. Therefore, domains are not classified as one of the basic building blocks alongside relations, tuples, and attributes.