Detailed explanation and options for the selected question.
What does the term "foreign key" refer to in a relational database?
A.
A key that links tables together
B.
A unique identifier for rows
C.
A key that allows NULL values
D.
A key that speeds up queries
Explanation:
A foreign key links tables by referencing a primary key in another table. It is not a unique identifier, query optimizer, or necessarily allows NULL values.