Answer:
There is no stated amount of time required
Explanation:
There is no stated amount of time required to which a Scientist can investigate his idea.
The least amount of investigations he is to carry out is one in order to make sure his findings are reproducible. He can go on to carry out as many as eight more investigations just to ensure his findings are correct and universally accepted.
I'm pretty sure that it is polarity I hope I am right and good luck, but I am pretty sure it's polarity
Answer
d.crust
Explanation
because he covered the layer of the earth
