Final answer:
Giardia duodenalis, also known as Giardia lamblia, is a parasite that can cause severe diarrhea and is transmitted through contaminated water, distinguishing it from other foodborne viruses and bacteria like norovirus, hepatitis A, Shigella, and Staphylococcus aureus.
Step-by-step explanation:
Out of the foodborne microorganisms listed, Giardia duodenalis is considered a parasite. This organism, also known as Giardia lamblia, is a waterborne protist that can cause severe diarrhea when ingested. It is transmitted through water contaminated with the stools of infected humans or animals, making it essential for food preparers to practice good hygiene to prevent contamination of food. Giardia is distinct from viruses such as norovirus and hepatitis A and from bacteria such as Shigella and Staphylococcus aureus which are other common causes of foodborne illness