According to the passage, brain scanning technology can reveal all of the following regions of person's brain EXCEPT the regions that:
Govern rational responses to challenging situations.
In the second paragraph, while the author mentions that brain scans can help isolate the parts that govern how we react to challenges, he does not say whether the responses are rational or not. The parts of the brain that determine a person's financial risk appetite and those that are activated while he's gambling have been identified by researchers. So A and B cannot be the answer choices.