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

Answer options:

A. A primary key column referenced by another column as a foreign key can be dropped if using the CASCADE option.
B. An UNUSED column`s space is reclaimed automatically when the block containing that column is next queried.
C. An UNUSED column`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

ABF