Final answer:
The lasting effect of the Atlantic slave trade, even after being declared illegal was the continued, albeit illegal, African slavery in the Americas and the socio-economic difficulties faced by freed Africans.
Step-by-step explanation:
The Atlantic slave trade had numerous long-lasting effects on the world, and specifically, Africa and the Americas. One of the primary lasting effects, even after the slave trade was declared illegal, relates to option A: African slavery in the Americas continued on a large scale. This practice persisted covertly despite the laws made to abolish it. Additionally, the abolishment of slavery and the end of the Atlantic slave trade led to significant socio-economic challenges. There were indeed not enough jobs for newly freed Africans, catalyzing lasting economic disparities. However, the claim that Africans were able to take back control of their native countries is inaccurate in the context of the immediate aftermath of the trade, as European colonization still impacted Africa quite significantly.
Option C, regarding the exploitation of indigenous peoples, must also be considered within the broader context of European colonial expansion, which indeed involved significant exploitation of native populations. However, this was not a direct consequence of the Atlantic slave trade being declared illegal. The consequence concerning African societies, and the void left in them due to the slave trade, has impacted the continent for generations, with social and political instability as just two examples of the enduring impact.