The ______ of smoking among women, formerly negligible, has grown to such a degree that lung cancer has become the chief causer of cancer-related deaths among women.
 
【正确答案】 D
【答案解析】 句意：女性吸烟的发生率达到如此高度(这在以前是被忽略了的)以至于肺癌已经成为女性因癌症相关疾病死亡的主要诱因。incidence发生率，具有影响的程度。ferocious极度的；凶猛的。affluence富裕，富足。impudence轻率，厚颜无耻。