It's a <span>Neolithic period </span>
Southern slaveholders did not want the Congress to take the power over, so slave trade while controlling foreign affairs. So they only let the Congress have power over trade, excluding slave trade, for next twenty years.
The correct answer is b
In the nineteenth century the knight of labor aimed to bring all types of workers to a union to improve working hours and working conditions for laborers. It aimed at uniting skilled and unskilled workers into a union.However, unlike the knight of work the american federation of labor focused on improving of wages, working hours and also avoiding general social reforms.