The next two questions refer to the following passage:
A pharmaceutical company tested a new painkiller on 1,000 lab rats that were fed large doses of the painkiller for a two-month period. By the end of the experiment, 39 of tile rats had died. The company concluded that the painkiller was sufficiently safe to test on humans.
Which of the following, if true, provides the most support for the pharmaceutical company’s conclusion ？（）
A. The amount of painkiller fed to the rats was substantially greater, in relation to body mass, than the dosage any human would take under normal circumstances.
B. Because of the different body chemistry of humans and rats, some compounds can be dangerous for rats but safe for humans, and vice versa.
C. Tests of this same painkiller on dogs showed that 3 out of 50 dogs developed lesions on their livers during the course of the experiment.
D. The researchers found that during the experiment, the rats showed a significantly lower sensitivity to pain than rats do under normal circumstances.
E. In an experiment of this length with this number of rats, it is not unusual for up to 50 rats to die during the experiment for reasons unrelated to the experiment itself.
