What is the typical description of Giardia lamblia cysts?

• A. Oval to ellipsoid, 8–12 μm, with four nuclei in mature cysts
• B. 2–4 μm and spherical
• C. 20–25 μm and elongated
• D. 15 μm with two nuclei

Answer: (A)

Recognizing Giardia lamblia cyst morphology is about the infective form's size, shape, and nuclear content. Giardia cysts are oval to ellipsoid and typically about 8–12 micrometers long. A hallmark feature of mature cysts is the presence of four nuclei, which helps distinguish them from the trophozoite stage that has two nuclei. The other descriptions don’t fit: a much smaller size would not be Giardia cysts, a much larger size isn’t characteristic, and describing two nuclei aligns with the trophozoite rather than the cyst.