Tables TABLE_A and TABLE_B in database TESTDB have the same data structure
(same columns with the same definitions). You wish to unload the data from
the two tables into a single file in PC/IXF format.
Which command(s) can be used to do this?

A.
EXPORT TO combined.ixf OF IXF SELECT * FROM table_a UNION ALL SELECT *
FROM table_b

B.
EXPORT TO combined.ixf OF IXF SELECT * FROM table_a, table_b

C.
EXPORT TO combined.ixf OF IXF SELECT * FROM table_a:
EXPORT APPEND TO combined.ixf OF IXF SELECT * FROM table_b;

D.
EXPORT TO combined.ixf OF IXF SELECT * FROM table a INTERSECT SELECT *
FROM table b