What best defines a computer virus?

• A. A device to back up files.
• B. A computer program designed to replicate itself by copying itself into other programs stored in a computer.
• C. A routine for cleaning malware.
• D. A password management tool.

Answer: (B)

A computer virus is a program that replicates itself by attaching or copying itself into other programs stored on a computer, so it can spread when those programs are run. The defining idea is this self-replication through infection of existing software, which allows the virus to propagate across files, programs, or systems as users work with their computer. Viruses often execute only when the infected host program runs, and they may cause harm by altering data, displaying unwanted messages, or consuming resources.

Backing up files is a legitimate safety tool, not a virus. A routine for cleaning malware is a remediation or removal tool, not a virus. A password management tool stores and autofills passwords, which is unrelated to the self-replicating, spreading nature of a virus.