Concept:Malware that does not replicate itself depends on user action to spread and never creates copies of itself.Explanation:A Trojan horse disguises itself as a legitimate program to trick users into installing it.Once installed, it performs harmful actions but does not copy itself or spread automatically.Memory resident viruses and boot sector viruses are true viruses that actively replicate by attaching to memory or boot sectors.A worm also self-replicates and spreads independently across networks without user action.Hence, the Trojan horse is the only option that does not replicate itself.Answer:A. Trojan horse