What is required for transduction to occur?

Transduction is a process of horizontal gene transfer in bacteria, primarily mediated by bacteriophages, which are viruses that infect bacterial cells. During transduction, a bacteriophage can package bacterial DNA during the lytic cycle and then introduce that DNA into a new bacterial host during infection. This process effectively allows genetic material to be transferred from one bacterium to another through the action of the virus, thus facilitating genetic variation and evolution among bacterial populations.

The other choices do not play a role in the transduction process. Direct contact between cells is characteristic of conjugation, another form of genetic exchange. Antibiotics are not involved in the genetic transfer mechanism but are instead used to inhibit bacterial growth. Plasmid formation is associated with another mechanism of gene transfer known as transformation, where bacteria take up free DNA from their environment, which is distinct from the role of bacteriophages in transduction. Therefore, the requirement of a bacteriophage is essential for transduction to occur.