The correct answer for this question would be option D. Kidney failure prevents the excretory system from operating when blood is not properly filtered, leaving waste in the blood. Waste products are usually excreted by the kidneys. High levels of waste products in the blood may mean that the kidneys are not working as they should. When these wastes products are not excreted, urea would be stuck in the body which would cause high toxicity. Hope this helps.
