农民为了防止鸟吃农作物，就把农作物上面用网全罩起来，结果导致农业害虫大量繁殖，使粮食减产．出现这种现象是因为农民破坏了（　　）

A．生产者的生存环境

B．分解者的生活习惯

C．食物链的原有状态

D．生态系统的非生物部分

The nurse is evaluating the effectiveness of airway suctioning. Which of the following outcome criteria is most appropriate

A．Respirations unlabored.

B．Decreased mucus production.

C．Hollow sound on chest percussion.

D．Breath sounds clear on auscultation.