求助！morphine 中毒 A选项GWD-29-Q40

懒猩猩

15. GWD-29-Q40Micethat have been given morphine are very likely to develop blood poisoning becausebacteria that normally reside in the intestine typically respond to morphine bymigrating into the bloodstream.  However,when mice are given both morphine and the new drug naltrexone, blood poisoningis much less frequent, although it does still occur.  These results provide support forresearchers’ prediction that naltrexone will turn out to be toxic to certaintypes of bacteria.
Which of the following,if discovered to be true, would most seriously weaken the support for theresearchers’ prediction?

A.     After being administered to mice, naltrexone does not passfrom the bloodstream into the intestine.
B.     Naltrexone inhibits morphine from triggering the migrationof intestinal bacteria into the bloodstream.
C.     Mice that have been given naltrexone but not morphine haveno greater risk of developing blood poisoning than do mice that have not beengiven either substance.
D.     The increased risk of blood poisoning is not the onlyharmful effect on mice of being given morphine.
E.      Conditions other than the presence of intestinal bacteriain the bloodstream can cause blood poisoning in mice.


我觉得这个问题有两个前提
1）bacteria that normally reside in the intestine typically respond to morphine bymigrating into the bloodstream
2）when mice are given both morphine and the new drug naltrexone, blood poisoningis much less frequent, although it does still occur
结论的得出隐含的条件就是细菌跑到血液了，而N又在血液中杀死了某种细菌，所以变得less fluquent.
就是说作用位置是在bloodstream

那么A选项不是恰好把这个隐含的假设给否定了，和假设题的not weaken不是一个道理么？
而B中的结论直接与premise2冲突了，如果是这样那么根本不会发生bloodprisoning啊~~~~




求助大牛解答啊~~~

sdcar2010

Your assumption is wrong. The passage says that N kills certain type of bacteria, but it does not specify how and where the bacteria are killed. It might be in the blood stream, it might not. And if N kills the bacteria in the intestines, then the bacteria would not pass into the blood stream.

B) on the other hand, matches the premises 1 and 2 well, and provides another way to explain the facts. The passage says in the presence of M and N, blood poisoning is less frequent. I do not see how B) is against premise 2.

fdrandom

选项A说naltrexone怎么样进入intestine，而结论prediction是说naltrexone对bacteria有毒。
怎么样进入intestine不能解释有毒没毒啊，A是无关的。