Waterways provide easy transportation. For example, rivers allowed merchants to come in and out of territories. Rivers also provided water for plants and foods to grow healthy. In fact, people could also drink and bathe in the water. Now, bathing may not have been that sanitary but it still provided a good service. Which, in conclusion, this attracted many to these areas where water was available.
Option C, a diverse selection of exported products, is the right answer.
The empire of Songhai was founded by Sonni Ali, a leader of the Songhai people who wanted to break away from the empire of Mali. The standing army of the empire assisted in the progress of trade throughout the empire. Though gold was the main commodity of the trade yet there was a huge variety of exported items including rubber and ivory. The people of the empire were known for their production of the useful crafts and for the artifacts that had a religious motif.
Answer:
an advance state of humans, Culture and Industry