Which atmospheric layer is represented by the f what are its characteristics?

The atmospheric layer represented by F is called the ionosphere. It is the upper layer of the earths atmosphere. It is ionized by solar radiation which has an electrical charge. Radio waves can be broadcast all over the world due to the radio waves reaching the ionosphere and reflecting back.

Cultural convergence is the theory that two cultures will be more and more like each other a very notable example of this is around the u.s.-mexico border, where 

The answer is    d.  central highlands