Why has Australia always been a continent with few people?

Why has Australia always been a continent with few people?
A、Because Australia is too far away from Europe.
B、Because Australia is the least mountainous and most level of the world's continents.
C、Because Australia is separated from the rest of the world by seas.
D、Because most of the continent is hot and dry.
【正确答案】：D
【题目解析】：澳大利亚一直是一个人口稀少的大陆，是因为大部分的大陆又热又干。