The correct answer is C) Military conquests spread over a wider range than ever before.
The statement that describes a way in which civilizations that existed between 600 BCE and 600 CE were different from earlier civilizations is "Military conquests spread over a wider range than ever before."
Many empires thrived during these years like never before. That was the case of the Roman Empire, the Chinese empire through its dynasties, and the Persian Empire. These empires used its military strength to conquer new territories. They levied taxes on these regions that sometimes provoked rebellions. Uprisings in the far away territories were difficult to control due to the distance. For instance, in those years, the Roman Empire controlled two-thirds of the known world, from Spain to the Middle East and some parts of North Africa.