Evaluate the following ALTER TABLE statement: ALTER TABLE orders - SET UNUSED (order_date); Which statement is true? 

Answer options:

A. After executing the ALTER TABLE command, you can add a new column called ORDER_DATE to the ORDERS table.
B. The ORDER_DATE column must be empty for the ALTER TABLE command to execute successfully.
C. ROLLBACK can be used to get back the ORDER_DATE column in the ORDERS table.
D. The DESCRIBE command would still display the ORDER_DATE column.

A