10.  At present, it is not possible to confirm or to refute the suggestion that there is a causal relationship between the amount of fat we eat and the ______ of heart attacks.
【正确答案】 A
【答案解析】 四个选项的意思分别是：incidence发生率；impetus动力；rupture破裂，绝交；emergence出现，发生。句意：脂肪的摄入量和心脏病的发病率有关联，目前对这种说法既不能肯定也不能反驳。据此可知，正确答案是A选项。