Compared to Chattel Slaves in the Past, Modern Slaves Today

Compared to chattel slaves in the past, modern slaves today are

A) more likely to be treated well because the world has become more humane.
B) more likely to be controlled by violence, the threat of violence, and/or debt.
C) more valuable, which gives the slave-holder incentive to provide a reasonable standard of care.
D) more educated and better able to defend themselves against unscrupulous slave holders.