单选题 Drinking more water is good for the rest of your body, helping to lubricate joints and ______ toxins and impurities.

【正确答案】 C

【答案解析】 screen out筛选出；knock out击倒，打破；flush out冲掉，排出；rule out取消，划去。根据句意，多喝水可以排出毒素和杂质，故选C。