What were the different forms of slavery in different historical periods and regions? I - In ancient Greece and Rome, slaves were used mainly for ...

What were the different forms of slavery in different historical periods and regions?

I - In ancient Greece and Rome, slaves were used mainly for domestic and agricultural work, and were considered property of their owners.
II - In China, there was no buying and selling of slaves, but people were enslaved for various reasons, such as selling their freedom to avoid starvation, being convicted of high treason, or being expelled from home.
III - In the Middle Ages, the crisis in agriculture led to the evolution of slavery and free colonization into serfdom, whose full form would characterize the relations of production in the feudal era.
IV - In Spain, only one-third of the population was free, and the rest were slaves and freedmen. The power of the lord over the serfs had limitations: the serf could not be killed or mutilated, acts punished with half the penalty reserved for cases of death and mutilation of free men.
a) Only I and II are correct.
b) Only II and III are correct.
c) Only III and IV are correct.
d) All statements are correct.