Better make that a double

You’ve made a configuration change to Windows 7 that has caused the operating system to hang, and now it won’t boot to the Windows 7 desktop. Which of these options would be the best next step?

A) Reinstall Windows as an in-place upgrade to retain all user data

B) Revert to the last full backup

C) Boot with a LiveCD and modify the registry changes manually

D) Load the Last Known Good Configuration

E) Go to lunch, and hope that everything is better when you get back