You are the network administrator for Fabrikam， Inc. Your network consists of a single Active Directory forest that contains one domain named fabrikam.com. The functional level of the forest is Windows Server 2003. Fabrikam， Inc.， acquires a company named Contoso， Ltd. The Contoso， Ltd.，network consists of a single Active Directory forest that contains a root domain named contoso.com and a child domain named usa.contoso.com. The functional level of the forest is Windows 2000. The functional level of the usa.contoso.com domain is Windows 2000 native. A business decision by the company requires the usa.contoso.com domain to be removed. You need to move all user accounts from the usa.contoso.com domain to the fabrikam.com domain by using the Active Directory Migration Tool. You need to accomplish this task without changing the logon rights and permissions for all other users. You need to ensure that users in usa.contoso.com can log on to fabrikam.com by using their current user names and passwords.  What should you do？（）