Your network consists of 1，000 client computers that run Windows XP. The computers do not have access to the Internet.   You plan to migrate 200 of the computers immediately to Windows 7. The remainder will be migrated over the next several months.   You need to plan the most efficient method for activating all of the computers.   What should you do？（）

• A、 Use the Key Management Service （KMS） for all the computers.
• B、 Use Multiple Activation Key （MAK） Independent for all the computers.
• C、 Use Multiple Activation Key （MAK） Proxy for the first 200 computers， and then use the Key Management Service（KMS） for the remaining computers.
• D、 Use Multiple Activation Key （MAK） Independent for the first 200 computers， and then use Multiple Activation Key（MAK） Proxy for the remaining computers.