Calcium oxalate crystals shape.

• A. Envelope-shaped
• B. Needle-like
• C. Square with an X
• D. Rhombus-shaped

Answer: (C)

Calcium oxalate crystals in urine have characteristic shapes that help you identify them under the microscope. In this question, the square with an X is the depiction used in the reference material to represent calcium oxalate crystals. The appearance comes from the way the crystal faces intersect in the common viewing plane, giving a distinct square outline with an internal cross pattern that is recognizable in many laboratory images. This is why it’s the best match for calcium oxalate crystals in this context. The other shapes describe different crystal types or forms seen in urine, which is why they’re not the preferred choice here.