Answer:
The answer to 7 is caravans, I'm pretty sure.
Explanation:
Option 'B' = changes in climate, had the greatest impact on pre-historic man.
Changes on the weather forced men to move periodically or cyclically, usually returning to their original location at various times. When they moved to colder climates, they would make clothing out of animal skins, to protect themselves. When the nomads learned how to plant, they didn't need to search for other places anymore.
The correct answer is Timbuktu. It became the greatest city because it was a melting pot for traders from all possible nations because it was wealthy and developed compared to other places. It was a cultural and a trading center because the ruler knew how to rule properly and made Timbuktu one of the greatest cities in the world.
A. East and West. Hope this helps!