Because that's the way it works and there is probably another strong reason
I believe the correct is the third option. It is important to preview sources before using them in your research because it reveals deeper concepts. Reading deeply the sources would allow you to have a deeper understanding of the sources and determine which parts of the sources are useful to your research.
Answer:
This is true, nobody can tell you if something is impossible. If you think it is possible, it is possible.
Explanation:
