Final answer:
The Baltimore classification system groups viruses based on how the mRNA is produced during replication. This classification allows viruses in each group to share similar modes of transmission.
Step-by-step explanation:
The Baltimore classification system groups viruses based on how the mRNA is produced during the replicative cycle of the virus. When classified this way, the viruses in each group share similar modes of transmission. For example, Group I viruses have double-stranded DNA genomes and replicate in the nucleus of the host cell, while Group VI viruses have single-stranded RNA genomes and replicate in the cytoplasm of the host cell.