Final answer:
The presence of Giardia lamblia is best detected using stool samples, which are examined for cysts and trophozoites or analyzed with immunoassays. The correct option is C.
Step-by-step explanation:
The most appropriate type of specimen for detecting the presence of Giardia lamblia is stool. Giardia lamblia, a waterborne protozoan, causes an intestinal infection known as giardiasis.
This parasite is typically diagnosed through the direct examination of stool samples, with methods such as a stool ova and parasite (O&P) exam, which look for cysts and trophozoites, or with immunoassays like ELISA and direct fluorescence antibody kits. The treatments often used include antibiotics such as metronidazole, tinidazole, and others depending on the stage of infection.
Therefore, the correct option is C.