How does a virus replicate?

A virus replicates by invading the cells of a living host, which is the essence of its replication process. Viruses are not capable of reproducing independently or self-replicating like living organisms. Instead, once a virus enters a host cell, it hijacks the cellular machinery to produce viral components. This involves the virus releasing its genetic material into the host cell and using the host's ribosomes, enzymes, and resources to manufacture new viral proteins and genetic material. These components are then assembled into new virus particles that can exit the host cell, often destroying it in the process, and go on to infect additional cells.

The other options do not accurately describe the replication process of viruses. For instance, while viruses can be transmitted through the air, this does not involve replication; rather, it pertains to how they spread. Similarly, viruses do not split into multiple viruses nor do they self-replicate in isolation, as they rely entirely on living cells for their reproduction.