Answer:
The correct answer to fill in the blank should be: "sources".
Step-by-step explanation:
"Sources" is the correct answer because it is a reference both to backgrounded arguments and reasons and causes for them all, at the same time. There could be other words to fill in the blanks, although there is no options to choose, what consequently promotes the idea that there is not much anyways. Therefore, the word "sources" is the perfect one because it reveals arguments, theoretical backgrounds, examples, materials, topics, subjects, listing points, reasons, causes, consequences, and more.