Which of the following organisms is an ectoparasite of farm animals?

A louse is an ectoparasite of farm animals. Ectoparasites are parasites that live on the outside of the host's body, feeding on blood or skin cells. Lice are small, wingless insects that attach themselves to the hair or feathers of animals and feed on their blood. They can cause itching, skin irritation, and reduced production in farm animals, such as cattle, sheep, and poultry. Lice are common in crowded or unhygienic conditions, making good management practices such as regular grooming, cleaning, and reducing animal density essential for their control. The other options listed, tapeworm, liverfluke, and roundworm, are all endoparasites, meaning they live inside the host's body.