You have an Exchange Server 2010 organization named contoso.com.Your company is Investigating a user named User1.You need to prevent User1 from permanently deleting the items in his mailbox. What should you run？（）

• A、Set-Mailbox User1 -LitigationHoldEnabled $true
• B、Set-Mailbox User1 -ModerationEnabled $true
• C、Set-Mailbox User1 -RetainDeletedItemsUntilBackup $true
• D、Set-Mailbox User1 -RetentionHoldEnabled $true