There are 50 states in the U.S.
Hope this helps!
The correct answer is bipolar disorder.
This type of a disorder is characterized by rapid change of moods - one day, a person might feel depressed and very sad, and the other, they might be experiencing extremely elevated moods. This is what happened to Marco in the case above - so he might need to start seeing a therapist or taking medicine.
B, goods can move freely between countries since there are no obstacles in the way of free trade between nations