An arthropod-borne disease is spread by which of the following?

The correct answer is that arthropod-borne diseases are primarily spread by insects. These diseases, also known as vector-borne diseases, rely on specific types of arthropods, predominantly mosquitoes, ticks, and fleas, to act as carriers or vectors for the pathogens. For example, malaria is transmitted by Anopheles mosquitoes, while Lyme disease is spread through tick bites.

Insects serve a crucial role in the transmission cycle of these diseases; they often acquire the pathogen while feeding on an infected host and then transmit it to a new host during subsequent feedings. The life cycle and behavior of these insects are key factors in the epidemiology of the diseases they transmit, making them critical components in understanding and controlling these health threats.

While human beings can be hosts to such diseases, they do not serve as the vectors for transmission in the way that insects do. Snails can be intermediate hosts for some parasites, but they are not classified under arthropods and do not function as a primary vector for arthropod-borne diseases. Air does not have a direct role in the transmission of these infections as they require a biological vector for spread.