How does an opportunity cost differ from a trade-off?

An opportunity cost is the loss of possible gain from other alternatives when one is chosen, a trade-off is the course of action given up to perform the preferred plan of action (or campaign or attack).

The British colonizers needed more slaves because there was heavy labor.

Explanation: As a result, more were being Brought to the United States and used for numerous reasons. When slavery ended the economy collapsed because slaves wouldn't get paid to work out in the fields filled with crops or whatever they needed to do. If the people wanted a servant they would have to pay them money.