Answer:
Large deposits of gold and iron ore to use as trade goods.
Explanation:
Ghana Empire became prosperous because of gold smelting and trading links with Southern Europe and Morocco during the middle ages. The Ghana Empire flourished because of its iron and gold smelting in West Africa. The presence of gold in Ghana helped gain influence in Africa, increase trans-Saharan trade, and trade with Europeans.
The correct answer is B - large urban areas became even larger.
This is logical when you consider the fact that building aqueducts improved (increased) the water supply of a particular area through which aqueducts were running. This in turn enabled people to more further away from water sources as water was being rerouted through different areas. And when we're talking in terms of large urban areas, this enabled the creation of more and more building in urban areas which increased their size.
Because they wanted to. Maybe they wanted careers. They where searching for something? Ask a veteran.