Final answer:
The rats administered with 40 ng/g BPA are considered the treatment group.
Step-by-step explanation:
In the given information, the rats administered with 40 ng/g BPA would be considered the treatment group. The treatment group refers to the group of subjects that receive a specific treatment or intervention, in this case, the administration of 40 ng/g BPA. The control group, on the other hand, would be the group that does not receive the treatment.