You have an Exchange Server 2010 Mailbox server.All users use Microsoft Office Outlook 2010 to access their mailboxes.You implement a policy that automatically deletes e-mail messages that are older than 90 days.You need to provide users with an alternate location to store email messages that are older than 90 days.Administrators must be able to find the messages in both locations when they perform multi-mailbox searches.What should you create？（）
- Aa .pst file for each user that is stored in a shared folder
- Ba Personal Archive for each user
- Ca journal rule
- Da Retention Policy