You want the ability to recovery any time within the last seven days and therefore you configured the recovery window retention policy using the command： RMAN> CONFIGURE RETENTIOH POLICY TO RKCOVFRY WINDOW OF 7 DAYS； After configuring the recovery window， you performed the database backup as follows：（）
- A Backup RB1 at log sequence number 12871 on 5th Jan
- B Backup RB2 at log sequence number 15622 on 12th Jan
- C Backup RB3 at log sequence 16721 on 15th Jan
- D On 20th Jan when the log sequence number was 18112 you realize that there Is a need to a point in time at the beginning of the recovery window. You have all an hived redo log files to date.