Correct option is (C) chanhudaro
Some of the oldest known structures which have served as citadels were built by the Indus Valley Civilisation, where citadels represented a centralised authority. Citadels in Indus Valley were almost 12 meters tall. The purpose of these structures, however, remains debated. Though the structures found in the ruins of Mohenjo-daro were walled, it is far from clear that these structures were defensive against enemy attacks. Rather, they may have been built to divert flood waters.
