Australia Finally Became an Island Continent When

Australia finally became an island continent when

A) India separated from Australia.
B) Australia drifted northwards from high latitudes to take up a position in mid-to-lower latitudes.
C) the strait between Australia and Antarctica opened 30 million years ago.
D) the sea-floor commenced spreading and the Indian ocean widened as Australia separated from Africa.
E) New Zealand drifted away from Gondwana during the late Cretaceous.