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 a customer 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.