Which statement best defines a computer worm?

• A. A type of software that, while not definitely malicious, has a suspicious or potentially unwanted aspect to it.
• B. Any software application in which advertising banners are displayed while a program is running.
• C. A self-replicating computer program that penetrates operating systems to spread malicious code to other computers.
• D. A program or command procedure that gives the appearance that it is useful but in fact contains hidden malicious code that causes damage

Answer: (C)

A computer worm is defined by its ability to propagate itself automatically across networks by replicating and spreading to other machines, often exploiting vulnerabilities in operating systems or software. This self-replication and automated spreading is what sets worms apart from other types of malware that require user action or don’t spread on their own. The statement describes a self-propagating program that targets other computers, which is exactly what a worm does. In contrast, the other descriptions refer to software that is merely potentially unwanted, ad-supported, or disguised to appear useful—techniques that don’t involve self-replication across systems.