You are the network administrator for Contoso Pharmaceuticals. Your network consists of a single  Active Directory forest that contains three domains. The forest root domain is named contoso.com. The domain contains two child domains named usa.contoso.com and europe.contoso.com. The functional level of the forest is Windows Server 2003. Each domain contains two Windows Server 2003 domain controllers named DC1 and DC2. DC1 in the contoso.com domain performs the following two operations master roles： schema master and domain naming master. DC1 in each child domain performs the following three operations master roles： PDC emulator master， relative ID （RID） master， and infrastructure master. DC1 in each domain is also a global catalog server. The user account for Nancy Buchanan in the europe.contoso.com domain is a member of the Medicine Students security group. Because of a name change， the domain administrator of europe.contoso.com changes the Last name field of Nancy’s user account from Buchanan to Anderson. The domain administrator of usa.contoso.com discovers that the user account for Nancy is still listed as Nancy Buchanan. You need to ensure that the user account for Nancy Anderson is correctly listed in the Medicine Students group. 
What should you do？（）