Final answer:
It is true that if the ON DELETE CASCADE clause is included when defining a PRIMARY KEY constraint and a row is deleted from the parent table, related rows in the child table will also be deleted to maintain referential integrity.
Step-by-step explanation:
If the ON DELETE CASCADE keywords are included when a PRIMARY KEY constraint is created, it is True that if a row is deleted from the parent table, any corresponding records in the child table are also deleted. The ON DELETE CASCADE action specifies that when a referenced row in the parent table is deleted, all rows with a foreign key that references that primary key in the child table will be deleted automatically. This is part of referential integrity in relational database management systems.