One major tectonic event that characterizes the late paleozoic eras is

The Paleozoic Era is bracketed by two major events in earth's history. It began with an unexplained explosion in animal life and ended with the world's largest mass-extinction known to man. The causes of these great events are currently unknown and under debate.

The correct answer is b, social stratification is needed for a society to exist. marxist theory regarding social stratification is that due to the differing economic capacities among people in society, a natural separation occurs between those that own the means of production and those that sell their labour in the production chain.