Which statement is true regarding the effect of the above SQL statement?

Evaluate the following SQL statement:
ALTER TABLE hr.emp SET UNUSED (mgr_id);
Which statement is true regarding the effect of the above SQL statement?

A.
Any synonym existing on the EMP table would have to be re-created.

B.
Any constraints defined on the MGR_ID column would be removed by the above command.

C.
Any views created on the EMP table that include the MGR_ID column would have to be
dropped and re-created.

D.
Any index created on the MGR_ID column would continue to exist until the DROP UNUSED
COLUMNS command is executed.