Concept:Viruses, worms, and Trojan horses are examples of malware, which is harmful software.
Explanation:Viruses, worms, and Trojan horses belong to the category of malicious software, also called malware.
Malware is designed to disrupt, damage, or gain unauthorized access to computer systems and data.
This category is different from system software, application software, or utility software, which serve normal or maintenance functions.
A virus attaches itself to legitimate files and spreads when those infected files are opened or executed.
A worm is self-replicating and spreads across networks without user action.
A Trojan horse appears harmless but hides a harmful purpose, such as stealing data or allowing unauthorized access.
Because all three are intentionally harmful, they are best classified as malicious software.
Answer:B. malicious software.