Final Answer:
Horizontal genetic transmission is facilitated by an infectious agent.
Step-by-step explanation:
Horizontal genetic transmission refers to the transfer of genetic material between organisms that are not parent and offspring. This process is commonly associated with infectious agents such as bacteria or viruses.
Unlike vertical transmission, which occurs from parent to offspring, horizontal transmission allows genetic material to be exchanged between unrelated organisms.
In the context of infectious agents, this can happen through mechanisms like conjugation in bacteria, where genetic material is directly transferred between cells. Gametes, on the other hand, are involved in vertical genetic transmission, passing genetic material from parents to offspring during sexual reproduction.