Which mechanism of gene transfer in bacteria relies on a bacteriophage?

Transduction is the mechanism of gene transfer in bacteria that specifically involves bacteriophages, which are viruses that infect bacteria. During transduction, a bacteriophage attaches to a bacterial cell and injects its genetic material. This can lead to the incorporation of bacterial DNA into the phage genome. When the phage replicates and subsequently infects another bacterial cell, it can transfer this bacterial DNA to the new host. This process allows for genetic material exchange between bacteria, potentially facilitating the spread of traits such as antibiotic resistance.

In contrast, transformation involves uptake of free DNA from the environment by a bacterial cell, and conjugation requires direct contact between two bacterial cells to transfer genetic material through a pilus. Bacterial fission is the process of a bacterial cell dividing to produce two daughter cells and does not involve gene transfer mechanisms. Thus, transduction is the only option that clearly involves bacteriophages in the transfer of genetic material.