Because it was an easy source of water for their needs that required it and it was also and easy way to transport supplies to the battle sight if an army was in a foreign location. Hope this helps, if you need clarification let me know?
actually the answer is d.worked at challenging jobs in the cities.
When you say "diversity" I think of many things. So I have many answers:
1. People. Different people farming, means different plants and animals
2. Planting Crops. Planting different crops can prevent soil erosion and or soil exhaustion.
3. On the market. Different crops and meats on the market provides consumers with different products and nutrients they may need.
Idk if this helps, there wasn't much detail. Hope it helps! ;)
