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?
Any synonym existing on the EMP table would have to be re-created.
Any constraints defined on the MGR_ID column would be removed by the above command.
Any views created on the EMP table that include the MGR_ID column would have to be dropped and re- created.
Any index created on the MGR_ID column would continue to exist until the DROP UNUSED COLUMNS command is executed.