Identify three situations in which you would NOT be able to drop a tablespace. （）
A. when the tablespace is online
B. when the tablespace has segments with data in it
C. when the tablespace is a default permanent tablespace for the database
D. when the tablespace contains a table that is currently being used by transactions
E. when the tablespace contains undo data that is needed to rollback an uncommitted transactio
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