______pollution control measures tend to be money consuming, many industries hesitate to adopt them.
【正确答案】 D
【答案解析】解析:在做此题时根据前后句意衔接,我们知道应该是因果关系,故答案只能为D。since在这里表示原因。although意为"虽然";however意为"然而;when意为"当…时候"。