Which three statements are true about dropping and unused columns in an Oracle database? (Choose three.)

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Which three statements are true about dropping and unused columns in an Oracle database? (Choose three.)

A. A primary key column referenced by another column as a foreign key can be dropped if using the CASCADE option.
B. An UNUSED columnג€™s space is reclaimed automatically when the block containing that column is next queried.
C. An UNUSED columnג€™s space is reclaimed automatically when the row containing that column is next queried.
D. Partition key columns cannot be dropped. E. A DROP COLUMN command can be rolled back F. A column that is set to UNUSED still counts towards the limit of 1000 columns per table