Multiple choice technology databases What is a primary key? The primary key column is a column or combination of columns whose values can be non-unique The primary key is a column or combination of columns whose values uniquely identify each row in the table The primary key is a column that can have NULL values all of above Reveal answer Fill a bubble to check yourself B Correct answer Explanation A primary key is a column or set of columns in a relational database table that uniquely identifies each row. Its values must be unique and cannot be NULL, making alternative options incorrect.