William specified the following initialization parameter settings in the pfile：   BACKGROUND_DUMP_DEST = ’u01/oradata/dir_A’   USER_DUMP_DEST = ’u01/oradata/dir_B’   DB_CREATE_FILE_DEST = ’u01/oradata/dir_C’   DB_CREATE_ONLINE_LOG_DEST_n = ’u01/oradata/dir_D’   William enabled the change-tracking feature because he does not want to scan the entire datafile during backup. What is the default storage location for the change tracking file？（）  

• A、 ’u01/oradata/dir_A’
• B、 ’u01/oradata/dir_B’
• C、 ’u01/oradata/dir_C’
• D、 ’u01/oradata/dir_D’