Which two statements are true in this scenario?

The database Is configured in ARCHIVELOG mode. The database needs to be up 24 X 7. You
want to perform user managed backup for the data files of the HR_DATA tablespace.
To accomplish the task, you issued the following command:
SQL> ALTER TABLESPACE hi_data BEGIN BACKUP;

Which two statements are true in this scenario? (Choose two.)

A.
No transaction on the tablespace is allowed but you can perform queries.

B.
The tablespace will automatically come out of backup mode when the file copy is complete.

C.
The checkpoint change number is frozen in headers of the data files until the file is removed
from backup mode.

D.
The database writes the before image of an entire block to the redo stream before modifying.
block tor the first time.