Dr. Hagiwara synthesized a new drug in her laboratory and discovered that it enhanced dopamine activity in the mesolimbic system of rats. What conclusions should Dr. Hagiwara draw from this finding?

A. There is no risk that the drug would be addictive to humans, because rats and humans respond to substances very differently.
B. Dr. Hagiwara should immediately try out the drug on some human volunteers to assess whether or not the drug is addictive.
C. Based on the information she has, Dr. Hagiwara cannot draw any conclusions about the addictive potential of her new drug.
D. There is a significant risk that the drug would be addictive to humans.

Answer: D