which two cases would you use an outer join?

In which two cases would you use an outer join? (Choose two.)

A.
Only when the tables have a primary key-foreign key relationship.

B.
The tables being joined have NOT NULL columns.

C.
The tables being joined have both matched and unmatched data.

D.
The columns being joined have NULL values.

E.
The tables being joined have only matched data.

F.
The tables being joined have only unmatched data.

Explanation:

:
You use an outer join to also see rows that do not meet the join condition.
Refer : Introduction to Oracle9i : SQL, Oracle University Study Guide, 4-17