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（）？
- ASet-Mailbox User1 -LitigationHoldEnabled $true
- BSet-Mailbox User1 -ModerationEnabled $true
- CSet-Mailbox User1 -RetainDeletedItemsUntilBackup $true
- DSet-Mailbox User1 -RetentionHoldEnabled $true