You are operating your database in the manual archiving mode. Currently， your database is configured with the following online redo log groups and members：    You tried to drop Group 1 from the database but received the following errors：        ORA-01623： log 1 is current log for thread 1 cannot drop        ORA-00312： online log 1 thread 1：   ’D:///ORACLE/ORADATA/TESTDB/REDO01a.LOG’   What might be the reason for these errors？（）  

• A、 Group 1 is an active or current online redo log group.
• B、 Group 1 is an inactive online redo group that has not been archived yet.
• C、 The members of the Group 1 are temporarily asymmetric with the members of other groups.
• D、 The size of the online redo log members of Group 1 is different from the size of the members in other groups.