You are the messaging engineer for your company. Your company has a Windows Server 2003 Active Directory forest that contains one domain named Contoso. You plan to deploy Exchange Server 2007.

You need to recommend an Active Directory design that meets the following requirements:

Prevent the Contoso enterprise administrators from managing Exchange mailbox settings.

Prevent Exchange server administrators from managing Contoso user accounts.

Use one administrative console to manage all mailboxes and associated access permissions.

Which Active Directory design should you recommend?