Hello!
Issac Newton's Law of Gravity was made by the one and only, Issac Newton.
He used his time to investigate and discover this law, so choice one, cheating is not correct. Choice three is also incorrect, because the world didn't know about this law, or so much about gravity during that time.
Thus, choice two is correct because it was created and written through his ideas.
So therefore, the answer is choice two, personal idea.
