Parasites that can infect humans through contaminated water, food, or vectors.

• A. Fungal pathogens
• B. Parasitic pathogens
• C. Bacterial pathogens
• D. Viral pathogens

Answer: (B)

Parasites are organisms that live on or inside a host and rely on it for nutrients, often causing disease. When we talk about infections acquired from contaminated water, food, or through vectors, we’re focusing on parasitic organisms that can be transmitted by those routes. Examples include protozoan parasites like Giardia or Cryptosporidium from contaminated water, helminths such as tapeworms or roundworms from undercooked or polluted foods, and vector-borne parasites like Plasmodium (malaria) transmitted by mosquitoes. These are all parasitic in nature, meaning they depend on a human host to complete their life cycles.

Other categories—fungal, bacterial, or viral pathogens—are indeed disease-causing agents, but they aren’t grouped by the same parasitic lifestyle and transmission pattern described in the question. The term that best fits all organisms that cause disease and rely on a host in this way is parasitic pathogens.