The important natural resource in West Africa that the Songhai Empire controlled was salt.
This salt was predominantly found in the Sahara desert - there are still a lot of salt mines in this West African desert. The Songhai Empire heavily relied on salt trade, which brought most of its money into the empire - this is the reason why it was so powerful at the time - because of salt and gold.
I believe the correct option is D. CONSTITUTIONAL
I think the correct answer from the choices listed above is option A. One of the most important legacies of the Northwest Ordinance was that it prevented the expansion of slavery in the north of the Ohio River in the newterritories. Hope this answers the question.
To transport troops and supplies
