An eighth grader named marianne consistently refuses to do difficult classroom assignments because she's afraid of failing at them. which one of the basic needs described in the textbook is marianne most clearly trying to address

The answer is "her need for competence".

Need for competence implies the want to control and ace the earth and result. We need to know how things will turn out and what the outcomes are of our actions. Competence advances the quest for testing and profoundly fulfilling encounters and is a foundation for mental development and prosperity. 

The geography affected the West African empires in that people settled to the south of the Sahara desert where it was more fertile. There were gold mines and salt mines in the area that gave them leverage in trade.

Explanation:

The three great empires of West Africa were Ancient Ghana, Mali, and Songhai. These societies flourish from 700 AD to 1600 AD. Their power and influence was largely based on their ability to trade. Trade was vital to these societies and they had to traverse the Sahara desert on camels to do so with North Africans who had trade relationships with the Middle and Far East, as well as Europe. In Ancient West Africa people began to settle south of the Sahara, where the land was more fertile. Villages and towns traded for items they could not produce themselves. The empires had access to gold and this gave them power in trade as well. Mali also had access to the Taghaza, an important salt-mine that also gave them leverage in trade.