Which description matches protozoa in the material?

• A. Protozoa are multi-celled organisms that live in the soil.
• B. Protozoa are larger bacteria that cause disease.
• C. Protozoa are viruses that infect cells.
• D. Protozoa are single-celled organisms that enter through food and water.

Answer: (D)

Protozoa are single-celled, eukaryotic organisms. In health material, they’re described as microscopic parasites that can be swallowed with contaminated food or water, leading to infections such as giardiasis or amoebic dysentery. This fits best because protozoa are cells with a nucleus and more complex structures, not multicellular like some organisms, not viruses, and not simply larger bacteria. Their transmission through contaminated food and water is a key way they cause illness, making this description the most accurate.