To alleviate the problem of contaminated chicken, the experts recommend that the government shift its inspection emphasis from cursory bird-by-bird visual check to a more ______random sampling for bacterial and chemical contamination.
【正确答案】 D
【答案解析】解析：rigorous“严格的，严峻的”；perfunctory“马马虎虎的”；symbolic“象征的”；discreet“小心的，谨慎的”。由句意可以推断出，此处应填与cursory“粗略的”意思相反的词，故应填谨慎的，故选D。