Has anyone seen my spot welder?

You have identified a malware infection on a critical computer at your organization. What is the best process to ensure that the malware is completely eradicated?

A) Update the anti-virus signatures and run a full scan

B) Install some anti-malware software and perform a malware removal

C) Recover from a restore point from a date prior to the infection

D) Format the hard drive and reinstall the operating system from a clean backup

E) Grab a hammer, a can of lighter fluid, and some ball bearings