Your network contains Exchange Server 2010 servers.  All users access their mailboxes by using Outlook Web App （OWA）. Your companys compliance policy states the following： .All e-mail messages that contain customer contracts must be stored for three years .Users must be able to classify e-mail messages that relate to customer contracts .Users must be able to move e-mail messages to any folder  You need to recommend a solution that supports the requirements of the compliance policy.  What should you recommend？（）

• A、Managed Folder mailbox policies
• B、an OWA mailbox policy
• C、Personal Archives and an Archive policy
• D、Retention Policy Tags and a Retention Policy