The primary reason for withholding food and fluids from a client who will receive general anesthesia is to help prevent

A. constipation during the immediate postoperative period.
B. vomiting and possible aspiration of vomitus during surgery.
C. pressure on the diaphragm with poor lung expansion during surgery.
D. gas pains and distention during the immediate postoperative perio

空气中的汽车尾气、吸烟形成的烟雾以及（）会影响呼吸系统和皮肤健康。

A.厨房油烟

B.沼气

C.天然气

D.二氧化碳