In a relational database with referential integrity, the use of which of the following keys would
prevent deletion of a row from a customer table as long as the customer number of that row is
stored with live orders on the orders table?

A.
Foreign key

B.
Primary key

C.
Secondary key

D.
Public key

Explanation:
In a relational database with referential integrity, the use of foreign keys would prevent events such
as primary key changes and record deletions, resulting in orphaned relations within the database.
It should not be possible to delete a row from acustomer table when the customer number (primary
key) of that row is stored with live orders on the orders table (the foreign key to the customer table).
A primary key works in one table, so it is not able to provide/ensure referential integrity by itself.
Secondary keys that are not foreign keys are not subject to referential integrity checks. Public key
is related to encryption and not linked in any way to referential integrity.