Which of the following diseases is caused by parasites?

The correct answer identifies a parasitic disease, which is defined specifically as an illness caused by parasites—organisms that live on or in a host organism and acquire nutrients at the host's expense. These parasites can include protozoa, worms, or ectoparasites like mites and lice.

Understanding the context of other diseases helps underscore why this answer is accurate. Occupational diseases are caused by exposure to hazardous conditions in the workplace, while viral diseases result from viruses, which are distinct organisms requiring a living host to replicate. Bacterial diseases arise from bacteria, which, like viruses, are separate from parasitic infections. Thus, identifying the disease caused specifically by parasites as a parasitic disease clarifies the unique nature of how these organisms affect health, prioritizing the way they differ from other pathogens.