The correct answer is - C) densely populated coastal settlements.
After the Europeans started to settle in Australia, the Aborigines suffered heavy blows. They were seen as primitive and as people that do not even even deserve to exist. That led to murdering lot of Aborigines in the coastal areas where the Europeans initially settled. Also, the diseases brought by the Europeans decimated the numbers of the Aborigines that were in contact with them, and very quickly their numbers went so low that they were on the verge of going extinct as people.