Songhai was best known for a

thriving trade of imported goods.
a dictatorial government that oversaw all aspects of the empire
a diverse selection of exported products
a system of taxation and wealth distribution

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.

i think the answer is the one about environmental and social health.

hope this