In Oracle Database 12c, regarding a full outer join:
A . It includes rows that are returned by an inner join. This is true. A full outer join includes all rows from both joined tables, matching wherever possible. When there's a match in both tables (as with an inner join), these rows are included.
D . It returns matched and unmatched rows from both tables being joined. This is correct and the essence of a full outer join. It combines the results of both left and right outer joins, showing all rows from both tables with matching rows from the opposite table where available. Options B, C, and E are incorrect: B is incorrect because the Oracle join operator (+) is used for syntax in older versions and cannot implement a full outer join by using (+) on both sides. Proper syntax uses the FULL OUTER JOIN keyword. C is incorrect as a Cartesian product is the result of a cross join, not a full outer join. E is incorrect because it only describes the scenario of a full anti-join, not a full outer join.
Reference: Oracle Database SQL Language Reference, 12c Release 1 (12.1)