Which statement about computer viruses is true?

• A. They are programs or code that replicates itself.
• B. They always strengthen the computer's defenses against threats.
• C. They are always detected by antivirus software.
• D. They originate from hardware failures.

Answer: (A)

A computer virus is defined by its ability to reproduce—its primary purpose is to copy itself and spread to other files or systems. This self-replication is what makes a virus distinct: it attaches to programs or data and then makes copies that move to new hosts, often causing harm in the process. That’s why the statement describing a virus as a program or code that replicates itself is the true description.

The other ideas don’t fit because viruses do not improve security; in fact, they undermine it by exploiting weaknesses and causing problems. Antivirus software does not guarantee detection of every virus—some variants are new or designed to evade signatures and heuristics. And viruses aren’t caused by hardware failures; they arise from software and how programs and data interact, often propagated through users’ actions or network activity.