How do viruses replicate?

Viruses replicate by invading live cells and utilizing the cellular machinery of those host cells to produce new virus particles. This process begins when a virus attaches to a suitable host cell and injects its genetic material (either DNA or RNA) into the cell. Once inside, the virus hijacks the host cell's ribosomes and other components to replicate its genetic material and synthesize viral proteins. As these components accumulate, they assemble into new viruses, which can then exit the host cell to infect other cells.

This mode of replication is fundamentally different from how bacteria divide, as bacteria can reproduce independently in various environments, and do not require a host cell. Additionally, while certain viral propagation methods can occur in laboratory settings, the essential characteristic of viruses is their dependence on living cells for replication. Therefore, the option indicating that they invade live cells for replication accurately captures the nature of viral reproduction.