Which of the following is not a function of the kidney?
Regulating blood pressure
Producing urine
Regulating blood glucose levels
Maintaining electrolyte balance
While the kidney has many important functions, such as regulating blood pressure, producing urine, and maintaining electrolyte balance, regulating blood glucose levels is not one of them. The primary organ responsible for regulating blood glucose levels is the pancreas, which produces insulin and glucagon. The kidney can be affected by high blood glucose levels over time, leading to diabetic nephropathy, which is a type of kidney disease. However, the kidney itself does not regulate blood glucose levels in the same way as the pancreas. Hence, option 3 is the correct answer.