Which of the following terms signifies an overwhelming quantity of information?

The term "copious" signifies an overwhelming quantity of information because it describes something that is abundant or plentiful. When used in the context of information, "copious" implies a vast amount, often to the point of being excessive or hard to manage. This term is frequently applied in academic or analytical discussions where a large volume of data must be considered.

The other choices convey different meanings: "inadequate" suggests not enough, "scarce" indicates a lack of something, and "limited" refers to being restricted in quantity or access. None of these terms imply abundance or excess, which is why "copious" is the term that best captures the essence of an overwhelming amount of information.