Explanation

Avast and NAV are anti-virus software

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Symantec's Norton Group launched Norton AntiVirus 1.0 (NAV) for PC and compatible computers.

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Avast's free antivirus software detects and blocks all types of malware in real-time to prevent them from infecting your computer.

Kaspersky, Norton, and Avast are anti-virus software

Linux is an operating system, not an anti-virus

Anti virus