Answer:
D
Step-by-step explanation:
The Aboriginal population was reduced when European colonists settled in Australia primarily because the Europeans brought violence and diseases with them, option D.
The arrival of Europeans in Australia in 1788 led to the spread of diseases such as smallpox, measles, and influenza, which the Aboriginal people had no immunity to. As a result, these diseases caused widespread sickness and death among the Aboriginal population. Additionally, European settlers also frequently engaged in violent conflicts with Aboriginal people over resources and land, leading to further loss of life.
The European colonists also settled on and claimed most of the Aboriginal land, option B. This often forced the Aboriginal people to relocate to less desirable and less habitable areas. Furthermore, Europeans also brought animals with them, option A, which often had a negative impact on the local ecosystems and disrupted the Aboriginal people's traditional way of life.
However, while the harsh environment of the Outback, option C, may have presented challenges to the Aboriginal people's survival, it was not a significant factor in the population reduction that occurred with the arrival of European colonists.