Which description best distinguishes a Trojan Horse from a virus?

• A. Trojan Horse is harmful software disguised as a normal file; virus spreads to other computers
• B. Trojan Horse spreads to networks; virus hides as a normal file
• C. Trojan Horse is a type of hardware; virus is software
• D. Trojan Horse encrypts data; virus deletes files

Answer: (A)

Think in terms of how each threat gets you to run it and how it moves between machines. A Trojan horse relies on deception: it hides inside a file or program that looks legitimate, so you run it because it appears harmless or useful. Once you execute it, it can do its malicious work, but it doesn’t automatically copy itself to other computers. A virus, by contrast, is built to spread. It attaches to other programs or files and replicates itself, moving to other machines when infected files are shared or executed. So a description that says the Trojan is disguised as a normal file and the virus spreads to other computers captures the essential difference between them.