What is the significance of the 'cities of refuge' established in the Old Testament, and how do they reflect God's justice and mercy in a society governed by blood vengeance?

A They were primarily centers of trade and commerce. B They were designed to punish those who committed accidental manslaughter, ensuring strict retribution. C They provided a sanctuary for those who accidentally caused a death, offering protection from blood relatives seeking revenge and allowing for a trial to determine guilt or innocence. D They were military outposts used to defend Israel from enemy attacks.