Why might you not be able to enforce referential integrity on a one-to-many relationship?

a. The table on the “one” side doesn’t have a matching record(s) in the table on the “many” side.

b. The table on the “many” side doesn’t have primary key field.

c. The table on the “many” side has values in the foreign key field with no matching value in the primary key field of the table on the “one” side.

d. The table on the “many” side has many values in the foreign key field with one matching value in the primary key field of the table on the “one” side.