You want to take the backup of the USERS tablespace. It has a single data file of 900 MB. You have tape drives of 300 MB each. The SBT channel is configured for Recovery Manager (RMAN). To accomplish the backup, you issued the following RMAN command: RMAN> BACKUP SECTION SIZE 300M TABLESPACE users; Which two statements are true about the execution of the above command? （）(Choose two.)

• A、The backup piece size will be limited to 300 MB
• B、The RMAN uses multiplexing to perform backup
• C、The operation is accomplished using the default channel available
• D、The RMAN parallelizes the backup although the parallelism is not set for a channel