What defines the fields a user must fill in to insert records?

The correct choice defines the fields a user must fill in to insert records through the insert definition displayed in the insert record dialog box. This definition lays out the specific requirements and constraints for data entry, guiding users on which fields need to be completed and how to format the information correctly.

The insert record dialog box is an interface element that offers a structured way for users to input data, ensuring that the necessary fields are clearly marked and that users understand the requirements for successful record insertion. By defining fields in this manner, the system maintains data integrity and consistency, preventing errors that may arise from incomplete or improperly formatted entries.

This understanding is crucial because it directly impacts how users interact with the database and ensures that essential data is captured accurately, aligning with business processes and compliance needs. Other options, while potentially relevant in different contexts, do not specifically pertain to the mandatory fields required for record insertion within the user interface.