The Circum-Atlantic belt and Southern Europe/Asia
One big difference between the two is that Saudi Arabia has very abundant oil reserves, which are the basis of its economy, and Yemen and Oman, despite being next to it, have very small oil reserves.
This also influences how rich the countries are, although in the recent years Oman is catching up on Saudi Arabia and it's not very poor.
I think its A. but not completely sure.
Answer:
The Cold War was an important influence on almost all aspects of American society. Cultural antagonism between the United States and Soviet Union had both positive and negative repercussions. Mutual fear between the two countries led to political confrontations; some of which nearly led to world war.