Question

Enslaved Africans were brought to brazil to...

Answer 1

Colonists were substantially dependent on autochthonous labour during the embryonic phases of settlement to conserve the subsistence economy, and natives were often seized by expeditions called bandeiras, originating in São Paulo. 
Slave labour was the driving might behind the maturation of the sugar economy in Brazil, and sugar was the key export of the colony from 1600-1650. 
Gold and diamond deposits were uncovered in Brazil in 1690, which triggered an expansion in the importation of African slaves to power this newly profitable market. Transportation systems were advanced for the mining infrastructure, and population improved from immigrants seeking to take part in gold and diamond mining. 
I hope this answered your question, and my apologies if this answer is wrong. Good luck on your quiz or homework.