Which of the following does not replicate itself in an infected computer?

Malicious software is grouped by how it behaves once it infects a computer. Self-replication, the ability of a piece of malware to make copies of itself and spread to other files or systems without further action from an attacker, is the key feature that separates some categories from others.

A worm copies itself across a network without needing to attach to another program, and a computer virus attaches itself to a legitimate file or program and copies itself whenever that file is run or shared, so both of these are defined specifically by their ability to replicate. A program that disguises itself as legitimate or useful software while secretly carrying out harmful actions behaves differently: once it is installed, it performs its damaging function directly, but it does not make copies of itself or spread on its own; a user must be tricked into installing it again elsewhere for it to appear on another machine.

Software that secretly monitors a user's activity and sends the collected information to a third party, without the user's consent, is designed purely for covert surveillance and data theft, not for spreading itself between systems, which is exactly why it does not replicate in the way a worm or virus does.

When a question asks about self-replication specifically, focus on the defining mechanism of each malware type rather than treating "harmful" as the deciding factor, since several harmful programs never copy themselves at all.