Ziggurats were built on high platforms to keep them safe from floods

The correct answer is - false.

Ziggurats's purpose was not to be made in the way that they will be safe from floods, but they had a totally different purpose, a religious one. All of the ziggurats were part of temple complex that also included other buildings. They were places that were not available for the ordinary people, but only the high aristocracy and priests were allowed in them to perform religious ceremonies. They were made in the Mesopotamian region by multiple people, like the likes of the Sumerians, Akkadians, Babylonians, Assyrians.