What is the central prophetic message within Obadiah's short book concerning Edom?

A A call for Edom to convert to Judaism and follow the Mosaic Law. B A prophecy of Edom's eventual assimilation into the kingdom of Israel. C A prediction of Edom's complete and utter destruction as a consequence of their pride and mistreatment of Israel. D A warning to Israel to avoid the idolatrous practices prevalent in Edom.