You issue the following command in Oracle: CREATE TABLESPACE DAT_TBS DATAFILE "dat_tbs.dbf" SIZE 2M;. Later queries against the database reveal that the tablespace is located in the /u01/oradata/oracle directory. Which of the following choices identifies how Oracle likely determined what directory to place dat_tbs.dbf file in?（）

• A、DB_CREATE_FILE_DEST 
• B、DB_CREATE_ONLINE_LOG_1 
• C、DB_CREATE_ONLINE_LOG_2
• D、The directory is an operating system-specific default value in Oracle that can neigher be specified manually nor changed