In the Old Testament, what was the purpose of the 'cities of refuge' established by Moses, and what specific criteria had to be met to seek asylum in one of these cities?

A To provide sanctuary for those fleeing war, requiring only residency within the city walls. B To offer temporary shelter for the poor and homeless, demanding only repentance for past sins. C To serve as trading posts and economic centers, accessible to any merchant seeking profit. D To protect individuals who had accidentally caused a death, requiring proof of unintentionality and a trial by the city elders.