If the MAXRETAIL Column of the PROMOTION Table Has Been

Multiple Choice

If the MAXRETAIL column of the PROMOTION table has been set as unused,which of the following commands is valid?​

A) ​ALTER TABLE promotion RESET maxretail USED;
B) ​ALTER TABLE promotion DROP COLUMN maxretail;
C) ​ALTER TABLE promotion DROP UNUSED COLUMNS;
D) ​both b and c