While Monitoring the space usage in your database that is in ARCHIVELOG mode you observed that the flash recovery area does not have enough free space to accommodate any more files and you do not have necessary permissions to add more space to it. Identify the two events that can occur in the event of a log switch？（）
- A An entry is created in the alert log file and the database instance continues to function normally
- B The log switch hangs occur for transactions until free space is available in the flash recovery area
- C The Oracle database server deletes a file that is on the obsolete file list to make free space in the flash recovery area
- D The database instance status is implicitly changed to RESTRICTED mode and file creations to the flash recovery area are prevented