I believe it is D, the reason being is because they form on their own, not from a living or dead organism. It can't be B because that is true, and the same for C. hope this helps, have an amazing day :)
Answer:
I think it can be best described as sets
Since the country has a smaller area and a large amount of people (although smaller than Australia) the ratio of land to people in New Zealand is much larger than the ration of land to people in Australia.
