I'd appreciate if you attached the article as well. But i'm 90% sure it's option D. A quick search reveals that it was dubbed Black Saturday due to rapid fire growth within Yellowstone park. Option D is really the only one that relates to that at all.
Hope this helps!
Answer:
I think its Option A ) Half
since in Australia there are total 10 types of minerals mined
and United States has 5 of those 10 minerals mined.
5 is half of 10 so....yeah thats it.