A The development of an extensive trading system whereby manufactured goods exchanged for slaves in West Africa
While the transatlantic slave trade did involve the exchange of manufactured goods for enslaved people, this option specifically focuses on the trading system before the effects of African migration and settlement in the New World, and therefore it is not an effect of that migration and settlement itself. The other options (B, C, and D) are direct outcomes of the migration and settlement of Africans in the Americas.