I can't see the question because it is blurry. I am sorry...
False. Strontium 90 has a half life of only 30 years, and as millions of years pass, about the time fossils have been around, most if not all of any strontium would have decayed.
Answer:
It could be used writing an essay or doing group projects for example you could divide the essay among your group like someone does the introduction and someone does the body or if you are wanting to write a story with people you can divide the different things you need in the story and assign parts to different people.
Explanation:
Answer: a. Secondary
Explanation:
Once soil is already present all you need are animals to re establish the ecosystem
