The correct answer is - C) English.
The English were the ones that started to settle in Australia, even though they were not the first Europeans to discover it. As they started to settle on the new continent, they soon found out that there are already people living there, the Aborigines.
The English were very cruel towards the Aborigines, but apart from the cruelty, they also brought diseases with them, diseases to which the natives were not used to and their immune system was not adapted to. The diseases that seem like nothing serious for the Europeans, like the small-pocks and the common cold, actually turned out to be devastating towards the natives, and they wiped out most of their population.