单选题 . ①In the 2,000-year period immediately before European contact, many native groups of the Northern Plains of North America specialized in big-game hunting, subsisting primarily on bison. ②Bison routinely became fat-depleted in the spring, reducing their nutritional value, yet these groups did not supplement their diets with the nutritious, fat-rich fish that were abundantly available. ③Malainey et al. find a possible explanation in late-eighteenth- and early-nineteenth century accounts from three frontiersmen who had adapted to lean-meat diets during extended periods in the plains. ④Each had an opportunity to consume fish after extended meat dependence and upon eating it, became weak and ill. ⑤Malainey notes that prolonged lean meat dependence renders the body incapable of digesting lipids (fats), perhaps explaining native hunters' fish avoidance.16. The author of the passage mentions accounts from three frontiersmen primarily in order to ______

A、 show how the frontiersmen's dietary choices were influenced by the native groups with whom they came into contact
B、 suggest that these frontiersmen had not adapted well to a diet composed primarily of lean meat.
C、 indicate what kind of diet was habitually followed by native big-game hunters of the Northern Plains.
D、 identify evidence for a hypothesis regarding native hunters' fish avoidance.
E、 call into question an assumption about the effects of fish consumption on people who have adapted to a lean-meat diet.

【正确答案】 D

【答案解析】 D：本题属于功能题。定位句是边境居民的“描述”，对应选项D的evidence。他们的描述说明习惯吃瘦肉的人吃鱼就会生病，这一证据解释了为什么土著猎人不吃鱼，因为土著猎人消化不了，对应选项D的a hypothesis。