Another name for kidney stones, is (Nephrolithiasis). Nephrolithiasis is the presence of calculi within the kidney. Nephrolithiasis is also the medical term for kidney stones.
So it's A. Nephrons
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Right after going to the restroom, right after making food (but some companies are more lenient than others, and right after touching something that may be unclean.
Answer:
to obtain oxygen from the external environmen
