You have an Exchange Server 2010 server that contains a single mailbox database.All users run Microsoft Office Outlook and Outlook Web App.You discover that users cannot restore e-mail messages from the Recover Deleted Items folder.You need to ensure that users can restore e-mail messages from the Recover Deleted Items folder.What should you do？（）

• A、From the Exchange Management Console （EMC）， modify the properties of the mailbox database
• B、From the Exchange Management Console （EMC）， modify the properties of the Mailbox server object
• C、From the Exchange Management Shell， create a management role and then assign the role to all users
• D、From the Exchange Management Shell， create a retention policy and then assign the policy to all users