The sloth bear, an insect-eating animal native to Nepal, exhibits only one behavior that is truly distinct from that of other bear species:the females carry their cubs (at least part-time) until the cubs are about nine months old, even though the cubs can walk on their own at six months.Cub-carrying also occurs among some other myrmecophagous (ant-eating) mammals; therefore, one explanation is that cub-carrying is necessitated by myrmecophagy, since myrmecophagy entails a low metabolic rate and high energy expenditure in walking between food patches.However, although polar bears’ locomotion is similarly inefficient, polar bear cubs walk along with their mother.Furthermore, the daily movements of sloth bears and American black bears which are similar in size to sloth bears and have similar-sized home ranges reveal similar travel rates and distances, suggesting that if black bear cubs are able to (26) keep up with their mother, so too should sloth bear cubs.
Which of the following, if true, would most weaken the author’s argument in lines 18-26 (“Furthermore … sloth bear cubs”)?
A.Cub-carrying behavior has been observed in many non-myrmecophagous mammals.
B.Many of the largest myrmecophagous mammals do not typically exhibit cub-carrying behavior.
C.Some sloth bears have home ranges that are smaller in size than the average home ranges of black bears.
D.The locomotion of black bears is significantly more efficient than the locomotion of sloth bears.
E.The habitat of black bears consists of terrain that is significantly more varied than that of the habitat of sloth bears.
E为什么不对，D怎么出来的？求指教。与上面提到的POLAR BEAR的LOCOMOTION有关吗？
Which of the following, if true, would most weaken the author’s argument in lines 18-26 (“Furthermore … sloth bear cubs”)?
A.Cub-carrying behavior has been observed in many non-myrmecophagous mammals.
B.Many of the largest myrmecophagous mammals do not typically exhibit cub-carrying behavior.
C.Some sloth bears have home ranges that are smaller in size than the average home ranges of black bears.
D.The locomotion of black bears is significantly more efficient than the locomotion of sloth bears.
E.The habitat of black bears consists of terrain that is significantly more varied than that of the habitat of sloth bears.
