Correct Answer:
D. Trojan Horse
The correct answer is Trojan Horse. A Trojan horse is a type of malware that disguises itself as legitimate software, tricking users into installing it. Once installed, it operates without the user's knowledge or consent, performing malicious actions, which perfectly matches the description.
- Phishing is a social engineering technique used to steal sensitive data, not a type of program that runs on a system.
- A Virus is malware that attaches to legitimate programs and spreads, but the defining characteristic of a Trojan is its deceptive installation.
- Adware primarily displays unwanted advertisements and is often installed with some form of user consent, unlike a Trojan's deceptive nature.