How do viruses reproduce?

Viruses reproduce by requiring a living host to multiply, which is essential to their life cycle. Unlike living organisms, viruses cannot carry out metabolic processes on their own; they lack the cellular machinery necessary for reproduction. Instead, they attach to a host cell and inject their genetic material into it. This process hijacks the host's cellular functions to produce new viral particles. Once inside, the viral genetic material takes over the host's biological processes, causing it to produce copies of the virus until the host cell is overwhelmed and often destroyed, at which point the newly formed viruses are released to infect other cells.

The other options do not apply to the reproduction of viruses. For instance, they do not divide in half or undergo binary fission, as these processes are characteristic of bacterial reproduction. Additionally, viruses cannot replicate independently in water or any other medium; they need a suitable living host to propagate.