Which of the following best describes "most" and "least"?

The correct choice is superlatives because "most" and "least" are terms used to express the highest or lowest degree of a quality or characteristic among three or more items. In this context, "most" indicates the maximum extent or the greatest quantity of a particular attribute, while "least" indicates the minimum extent or the smallest quantity of that attribute.

For example, in the context of evaluating heights among a group of people, saying someone is "the tallest" would involve using a superlative form, just like saying someone is "the shortest" when discussing the least height. These words denote extreme positions within a given set, focusing on comparison rather than a simple comparison between two items, which would use comparatives.

The other options do not accurately describe the relationship that "most" and "least" convey. Comparatives would refer to comparing two items (like taller or shorter), and ignorants and negatives do not pertain to this grammatical structure at all. Thus, superlatives is the most fitting choice to describe "most" and "least."