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?

A. After being administered to mice, naltrexone does not pass from the bloodstream into the
intestine.
B. Naltrexone inhibits morphine from triggering the migration of intestinal bacteria into the
bloodstream.
C. 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.
D. The increased risk of blood poisoning is not the only harmful effect on mice of being given
morphine.
E. Conditions other than the presence of intestinal bacteria in the bloodstream can cause

OA is B

Can someone explain why B is correct? Doesn't C state that Naltrexone is not harmful so thereby weakening the conclusion that naltrexone will turn out to be toxic
blood poisoning in mice