Issue following BACKUP command to create data file backup set:

FORMAT /BACKUP/df_%d_%s_%p.bus
DATABASE filesperset =3 ;

Which two statement are true?
a. The control file was NOT backed up
b. Each data file was copied three times
c. A channel was automatically allocated
d. The archived redo log file were backed up
e. The database was mounted or open when the backup occured.

Can you explain this.. This is from STS 032