Final answer:
The presence of cities is a fundamental characteristic of a civilization, reflecting a society's capacity for surplus agriculture, social complexity, and urban development.
Step-by-step explanation:
Among the given choices, A) Cities is a characteristic of a civilization. The term "civilization" is most fundamentally associated with the presence of urban settlements or cities. Early civilizations typically arose along large rivers where sustainable agriculture generated surplus food, allowing for population growth, social specialization, and the emergence of cities. Within these urban centers, a complex society developed, including government organization, cultural enlightenment, and technological progress, all of which differentiated early civilizations from other forms of societies.