Mice that have been given morphine are very likely to develop blood poisoning because bacteria that normally reside in the intestine typically respond to morphine by migrating into the bloodstream.  However, when mice are given both morphine and the new drug naltrexone, blood poisoning is much less frequent, although it does still occur.  These results provide support for researchers’ prediction that naltrexone will turn out to be toxic to certain types of bacteria.

Which of the following, if discovered to be true, would most seriously weaken the support for the researchers’ prediction?

1. After being administered to mice, naltrexone does not pass from the bloodstream into the intestine.
2. Naltrexone inhibits morphine from triggering the migration of intestinal bacteria into the bloodstream.
3. Mice that have been given naltrexone but not morphine have no greater risk of developing blood poisoning than do mice that have not been given either substance.
4. The increased risk of blood poisoning is not the only harmful effect on mice of being given morphine.
5. Conditions other than the presence of intestinal bacteria in the bloodstream can cause blood poisoning in mice.

 请问这道题的答案是B吗?我选的是A,为什么不对呢?请NN指点一下

 请问这道题的答案是B吗?我选的是A,为什么不对呢?请NN指点一下

A不对，因为还有可能是细菌从肠道转移至血管然后那里被N杀死

B是他因削弱。

请教各位大大们，这题Ans:B

想请问各位大大为何A选不好因为细菌通常居住在intestine那N没有进入到肠不也weaken不会对细菌有害!!!!请大家帮帮忙~.~