A、Gold miners from Europe and China. B、Relatives of the previous immigrants C、Refugees from war and political problems. D、Escape

Australia is one of the most multicultural countries in the world. Almost one in every four people in Australia was born in another country: 4.8 million people out of a total population of 21 million.
    A little more than 200 years ago, Australia was inhabited by about 350,000 native people of many different cultural groups. Then, in 1770, the explorer James Cook sailed along the coast and brought back information about the "new" land to England. Seventeen years later, the British government started sending criminals and poor people to Australia. Later, free settlers came to Australia to start farms. In 1850, gold was discovered there, and more and more people came from Europe and China hoping to get rich. Most of them never returned home, so the population began to grow.
    Migration is still growing. In 2007, more than 177,000 people went to Australia to live permanently. Four main types of people settle there. Some go there because employment and business opportunities are better than in their home country. Others are the children, parents, or other relatives of immigrants who have become Australian citizens.[17]A third group is refugees who are escaping from war or political problems in their home countries. Finally, there are also a few Australians who migrated to another country and now want to come home.
    At the same time,[18]Australia also sends immigrants to other countries — a smaller number. Each year, about 60,000 Australians go to live permanently in other countries. With people from so many cultures migrating in and out, Australia is truly a diverse nation.
16. What happened after the news of the "new" land was brought back to England?
17. What are the third type of settlers to Australia according to the passage?
18. How many Australians emigrate to other countries each year?