A system administrator needs to quickly migrate a machine from AIX 5.1 to AIX 5.2. The administrator will only be allowed enough downtime to reboot the machine. Which installation method should be used to accomplish this task？（）

• A、Perform a migration installation during the reboot process.
• B、Perform an alternate disk installation and migration using NIM.
• C、Copy the /usr directory from another 5.2 server to this server.
• D、Perform an update_all install from 5.2 media to take effect on reboot.