What is the main difference between the Pan American Games and the Olympic Games?

AThe Pan American games are held every 6 years, while the Olympic Games are held every 4 years.
BThe Pan American Games are held in Buenos Aires, Argentina, while the Olympic Games are held in different cities all over the world.
COnly countries in the Americas and Caribbean participate in the Pan American Games, while Olympic Games are international.***
DThe Pan American Games do not allow professional athletes to compete, while the Olympic Games do.