Slavery occurred throughout the continent from the period of British colonization, in 1788-1868. specific groups of people including convicts, indigenous Australians and people transported from Asia and the pacific islands were made to labor in conditions which were either unpaid or under unilateral indenture contracts which were commonly not fulfilled.
The south didn't grow crops very much, instead they grew cotton which made them rely on the North for crops and other materials. So the correct answer would be "B" since that seems like the most plausible answer.
Someone lamenting about the "glass ceiling" would be concerned about workplace discrimination, letter A. This metaphor was created for feminists to illustrate the invisible barrier that keeps women to achieve the same professional achievements as men. Barriers such as the gender pay gap ( the difference between male and female in earnings) and the glass escalator (when men join fields that were previously occupied mainly by women) are examples of this phenomenon.
The Appilachian mountains was the greatest barrier, because it was crawling with Indian's that may have made them turn back.