Concept:A foreign key is a field that creates a connection between two tables in a relational database.
Explanation:Each table usually has a primary key, which uniquely identifies its records.
A foreign key in one table refers to the primary key of another table.
This reference allows related data to be accessed across tables.
For example, a foreign key like
StudentID links an enrolment table to the students table.
Using this foreign key, records from both tables can be matched and combined.
This makes it possible to retrieve student details along with their enrolled courses.
A foreign key does not ensure uniqueness in its own table.
Uniqueness of tuples or records is handled by the primary key or unique key.
So options A, C, and D describe the primary key, not the foreign key.
The foreign key specifically provides a link between data in two tables.
Answer:Option B: provide a link between data in two tables.