Which of the following describes something in a database that refers to the unique identifier...

 A foreign key is a column or a set of columns in a table that refers to the unique identifier (or primary key) in another table. A foreign key establishes a relationship between two tables and ensures referential integrity. For example, in a database that stores information about students and courses, the student table may have a column called student_id that is the primary key for each student record. The course table may have a column called student_id that is the foreign key that refers to the student_id in the student table. This way, the database can link each course record to the corresponding student record34. References := CompTIA IT Fundamentals (ITF+) Study Guide, 2nd Edition, Chapter 5: Database Fundamentals2; What is RDBMS (Relational Database Management System) - Javatpoint5; What is a Relational Database Management System? | Microsoft Azure6