Which of the following cultural advancements set the classical era apart from previous time periods?
a. the relative isolation of mesoamerican cultures
b. the urbanization of human populations
c. the establishment of trade between civilizations
d. the growth of empires across the entire region

“the battle of stalingrad is not a turning point necessarily in strategic terms, because a lot more has to be done before the soviets can be certain of defeating germany,” says renowned world war ii historian richard overy. the germans had fought nearly a thousand miles across the soviet union to get to stalingrad.