Answer: The first one is 4, the second one is 1, the third one is 3, the fourth one is 2.
Explanation:
Really I have never heard that before.
Answer:
scientific theories are mostly approved after they have been researched fully and can be backed up with evidence.
Explanation:It is less unlikely that the theory will change except that it can be improved when the new evidence is discovered due to the fact that they are based on discovered evidence.
Theory of gravity for example there is a proven evidence that there is a pulling force knows as the force of gravity that keeps us from floating on earth whereas in space the lack of that force causes one to float this is backed up by evidence that are visible and can be tested all over again.
It is important because the sources tell you whether the article was credible. When you have an article that has bad source, you are running the risk of having, wrong, opinionated data. This can discredit you paper if you use it.