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 the RMAN. To accomplish the backup， you issued the following RMAN command：   RMAN> BACKUP SECTION SIZE 300M TABLESPACE users；   Which two statements are true regarding the execution of the above command？（）

• A、 The RMAN parallelizes the backup although the parallelism is not set for a channel.
• B、 The backup piece size will be limited to 300 MB.
• C、 The operation is accomplished using the default channel available.
• D、 Three channels for the tape drive must be configured by setting the parallelism to three.