Examine the following output： SQL> SELECT index_name，status FROM dba_indexes WHERE status=’UNUSABLE’； INDEX_NAME STATUS------------------------------ ----------- EIND UNUSABLE Which two statements about the above index are true（）

• A、It is ignored by the query optimizer.
• B、It is not used while the index is being rebuilt.
• C、The index cannot be rebuilt， and has to be re-created.
• D、The index is automatically rebuilt when used the next time