A technician is alerted to a virus on a PC. The technician isolates the PC from the network. After verifying there are no other infected PCs on the network, which of the following is the SAFEST…

Applying a security patch closes the exploit pathway but does not remove malware code that has already been installed and may be persisting on the system.

System Restore reverts protected system files and registry keys to a snapshot but does not touch user-space files or locations outside the restore scope, leaving malware that stored itself outside those boundaries intact.

Reimaging overwrites the entire OS installation, removing all malware, backdoors, and persistence mechanisms without exception since nothing from the compromised environment survives. Applying all latest patches immediately after reimaging closes the known vulnerabilities that were exploited, preventing reinfection through the same vector and leaving the machine in a verified clean and hardened state.

A second antivirus tool may quarantine detected threats but provides no guarantee of complete removal, particularly for rootkits or fileless malware that evade signature scanning.