John is a merchant. He has set up a LAN in his office. Some important files are deleted as a result of virus attack. John wants to ensure that it does not happen again. What will he use to protect…

Backup protects against data loss by enabling recovery after an incident but does not prevent a virus from infecting the system or deleting files in the first place.

Symmetric encryption protects data confidentiality in transit or at rest but has no capability to detect or stop virus execution.

A firewall controls network traffic based on rules and can block some network-based threats, but it does not scan for or remove viruses already present on a local system.

Antivirus software scans files, processes, and storage for known virus signatures and heuristic patterns, providing real-time protection against virus infection and removal of existing threats. It directly addresses the problem of virus attacks that caused the file deletions John experienced. Regular definition updates allow antivirus tools to protect against newly discovered viruses as well.