Which city is recognized as the oldest in terms of human settlement history?

B is recognized as the correct answer because Eridu is often cited as one of the world's oldest known cities, with archaeological evidence suggesting continuous human settlement dating back to around 5400 BCE. Located in ancient Mesopotamia, Eridu is significant for its role in the early development of urbanization and civilization, particularly within the context of Sumerian culture.

The importance of Eridu lies in its historical context; it is viewed by some scholars as the first city in the world, a key site for the study of early urban life, religious practices, and social organization. Its layers of ancient architecture, including temples, support its status as a primary center of early civilization.

While Babylon, Constantinople, and Mohenjo-Daro are also vital in the narrative of human history, they emerged later or represent different aspects of civilization. Babylon was a mighty city-state but arose after Eridu, while Constantinople (modern-day Istanbul) was established as Byzantium and later became significant during the Roman Empire. Mohenjo-Daro, part of the Indus Valley Civilization, also reflects advanced urban planning but developed around 2500 BCE, considerably later than the establishment of Eridu. Thus, Eridu stands out as the oldest in terms of