Which of the following statements about slavery is true?
a
it began with the spanish and portuguese transatlantic slave trade.
b
it first began in africa in the 1500s and then spread to others parts of the world.
c
it had existed all over the world in various forms for thousands of years.
d
it existed only in africa before the sixteenth century.

Why was the monroe doctrine necessary?

For in this unit, you read about transitions of power and the formation of newly independent nations in africa, asia, the americas, and the middle east. some of these transitions were peaceful, while others caused long-term instability. why do you think some countries were more successful than others with political transitions? what do you think were the biggest challenges facing newly independent countries? would it have been possible for leaders to prevent these problems before they happened? why or why not?

Brainliestttme : ) what are trading blocs and what is the impact of international cooperation?