Slaves were used in the American colonies to perform labor because A. there were not enough workers.
America needed workers, but there were not enough people willing to perform such difficult jobs for basically no money at all, which is why they brought slaves who had to work for free.
I think that you answer is B physical labor
What do you mean colonies? You mean the 13 colonies?
work on plantations which might include but not limited to: picking cotton,farming,cleaning after animals and collecting crops. female slaves often worked as house maids or sadly sex slaves