Which type of malware is able to propagate itself without user interaction?

A.
Rootkit

B.
Trojan

C.
Virus

D.
Worm

Explanation:
Answer D is correct; the distinguishing feature of a worm is its ability to spread without user interaction. This capability has resulted in worms being able to rapidly infect millions of systems in a short period of time.

Incorrect Answers and Explanations: A, B, and C: Answers A, B, and C are incorrect. The main distinguishing feature of a rootkit is its ability to hide itself from a system administrator. A Trojan horse is malware that masquerades as something a user might want. A virus attaches to an executable and requires user interaction for spreading.