I am going to say 1 because it started 2.5 billion years ago and is still hapinung today
Answer:
Aging populations
Explanation:
The industrialized countries are facing a big demographic problem in the past few decades. The problem is the aging population. The living conditions in this countries are the best in the world, so they have high life expectancy, and while that is good, a problem occurs because the birthrates are very low. The birthrates are so low that they can not even simply sustain the same number of the population. This situation leads to fewer and fewer young people, and more and more elderly people, so the population pyramid is becoming wider at the top and narrower at the bottom.
mostly low plateau with deserts, rangelands and a fertile plain in the southeast; mountain ranges in the east and south-east. The geography of Australia encompasses a wide variety of biogeographic regions being the world's smallest continent but the sixth-largest country in the world.Australia, Zealandia, and New Guinea are continental islands. These three regions share some physical features. All three have mountain ranges or highlands—the Great Dividing Range in Australia; the North Island Volcanic Plateau and Southern Alps in New Zealand; and the New Guinea Highlands in Papua New Guinea.Australia is the smallest of the world's continents. It is also the lowest, the flattest and (apart from Antarctica) the driest. The highest point on the Australian mainland is Mount Kosciuszko, New South Wales, at 2228 metres above sea level.
