You are upgrading your single master Windows NT Server 4.0 network to Windows 2000. Which computer should you upgrade first?

• The stand-alone server in the Windows NT 4.0 domain that will become the root domain in your Windows 2000 network
• The primary domain controller (PDC) in the Windows NT 4.0 domain that will become a child domain in your Windows 2000 network
• The backup domain controller (BDin the Windows NT 4.0 domain that will become a child domain in your Windows 2000 network
• The Primary domain controller (PDC) in the Windows NT 4.0 domain that will become the root domain in your Windows 2000 network