How did the west African kingdoms become wealthy select the best answer from the choices below

Ghana's rulers gained incredible wealth from trade, taxes on traders and on the people of Ghana, and their own personal stores of gold. They used their wealth to build an army and an empire. Extensive trade routes brought the people of Ghana into contact with people of many different cultures and beliefs.

Explanation:

states began imposing duties on each other's goods. congress had no way to raise money for an army to expel them.

observing traffic laws in exchange for driving on the highway.