Which statement correctly explains when you would use ASSUMETARGETDEFS?

Which statement correctly explains when you would use ASSUMETARGETDEFS?

A.
The target tables are already created.

B.
Only the fields in the target tables are mapped.

C.
The source and target tables have identical data structure.

D.
You have specified wildcards in either the TABLE or MAP parameters

Explanation:
http://download.oracle.com/docs/cd/E15881_01/doc.104/gg_wux_ref_v104.pdf