Upon starting your database， you receive the following error：  
SQL> startup ORACLE instance started. 
Total System Global Area 171581440 bytes Fixed Size 1298640 bytes Variable Size 146804528 bytes Database Buffers 20971520 bytes Redo Buffers 2506752 bytes Database mounted. 
ORA-00313： open failed for members of log group 1 of thread 1 
ORA-00312： online log 1 thread 1： ’/oracle01/oradata/orcl/redo01.log’ ORA-00312： online log 1 thread 1： ’/oracle01/oradata/orcl/redo01a.log’  
You can choose from the following steps：  
a. Restore the database datafiles. 
b. Issue the alter database clear unarchived logfile group 1 command.
c. Issue the alter database open command. 
d. Issue the alter database open resetlogs command. 
e. Recover the database using point-in-time recovery.
f. Issue the Startup Mount command to mount the database. 
g. Back up the database. 
Which is the correct order of these steps in this case？（）