Which type of malware spreads from one system to another or from one network to another and causes similar types of damage as viruses do to the infected system?

A rootkit is designed to conceal malicious activity and maintain privileged access on a compromised system, but it does not self-propagate across networks.

A Trojan disguises itself as legitimate software and requires a user to execute it, meaning it does not autonomously spread from system to system.

A worm is a standalone malicious program that replicates itself and propagates across networks and systems without needing to attach to a host file or require user interaction. Unlike viruses, worms spread autonomously by exploiting network vulnerabilities or open shares, and they cause similar types of damage including file corruption, system slowdowns, and data destruction.

Adware delivers unwanted advertisements to users and does not replicate or spread independently across systems or networks.