Civilization is a very advanced and well-organized human society from all the other societies of that period. The required answer for this question is military strength.
Military strength is the correct choice as many early civilizations didn't maintain a strong army. There was a presence of warriors, but they were not well organized because, in these civilizations, people were mostly concerned more about their own settlement first, and then they started to think about increasing their military strength
Religion is an incorrect choice as in all the earliest civilizations; human beings practiced religion. The rulers of this civilization have claimed about getting power from the god himself or having the divine approval required to rule the citizens.
The social structure is also an incorrect choice as all the early civilizations had a social structure through which the humans practiced their occupation. In many civilizations, rulers and upper-class priests had more importance, and then came the other government officials and the warriors. The social structure was further classified into artisans, farmers, etc.
Food surplus is also an incorrect choice as these civilizations had advanced in agriculture practices, such as the irrigation system. All these agricultural settlements had resulted in the presence of surplus food.
Learn more about the early civilizations here:
https://brainly.com/question/17216986
