Which offense involves malware that replicates itself to spread to other systems?

The correct answer is a worm. Worms are a type of malware that are specifically designed to replicate themselves and spread across networks without needing to attach themselves to a host file, unlike other types of malware. They exploit network vulnerabilities to gain access to other systems and can propagate rapidly, which often leads to significant disruption.

Trojan, while a serious threat, serves a different function as it disguises itself as legitimate software to trick users into downloading it, rather than focusing on replication. Spyware primarily gathers information from the user's device without their consent, and while it can cause harm, it does not focus on self-replication. Ransomware, on the other hand, encrypts the victim’s files and demands a ransom for the decryption key, and does not replicate itself across systems.

Thus, the distinguishing feature of a worm is its ability to self-replicate and spread independently, which precisely defines its role in the malware landscape.