Answer the following question given this paragraph: 

Kidney stones are mineral crystals that form in urine inside the kidney. They may be extremely painful. If they block a ureter, they must be removed so urine can leave the kidney and be excreted.


Q: What kind of health problem can occur in the kidney and potentially cause problems with urination?

 Choices:

- infection

- diabetes

- gallstones

- kidney stones

A:
kidney stones
