A developer is designing a table that does not have repeated values.

The index that the developer should use to prevent duplicate values from being inserted is unique. A unique index is a type of index that enforces the uniqueness of the values in one or more columns of a table. A unique index ensures that no two rows in the table have the same value or combination of values in the indexed columns. A unique index helps to maintain data integrity and avoid data duplication or inconsistency. The other options are either not related or not effective for this purpose. For example, a single column index is a type of index that involves only one column of a table, but it does not prevent duplicate values unless it is also unique; an implicit index is a type of index that is automatically created by the database system when a constraint or a primary key is defined on a column or columns of a table, but it does not prevent duplicate values unless it is also unique; a composite index is a type of index that involves two or more columns of a table, but it does not prevent duplicate values unless it is also unique. References: CompTIA DataSys+ Course Outline, Domain 1.0 Database Fundamentals, Objective 1.2 Given a scenario, execute database tasks using scripting and programming languages.