Examine this syntax which allocates channels during a parallel image copy： RMAN> CONFIGURE DEVICE TYPE disk parallelism 4： 2> COPY 3> datafile 1 TO ‘/BACKUP/datafile1.dbf’， 4> datafile 2 TO ‘/BACKUP/datafile2.dbf’， 5> datafile 3 TO ‘/BACKUP/datafile3.dbf； RMAN>COPY 2> datafile 4 TO ‘/BACKUP/datafile4.dbf’； How many channels are used？（）
- A0
- B1
- C3
- D4