Which two are true about unused columns? (Choose two.)
A. A query can return data from unused columns, but no DML is possible on those columns.
B. Unused columns retain their data until they are dropped.
C. Once a column has been set to unused, a new column with the same name can be added to the table.
D. The DESCRIBE command displays unused columns. E. A primary key column cannot be set to unused. F. A foreign key column cannot be set to unused.
Which two are true about unused columns? (Choose two.)
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