Which term refers to the category of classes of paper?

The term that refers to the category of classes of paper is "grade." In the context of paper, grade classifies the quality and type of paper based on various factors such as its composition, surface finish, weight, and intended use. Different grades of paper may have specific characteristics that make them suitable for particular applications, whether it be for printing, writing, or artistic endeavors. Understanding paper grades helps designers and printers choose the right type of paper for their projects to achieve the desired quality and performance.

On the other hand, caliper refers specifically to the thickness of the paper, resolution pertains to the detail contained in an image or print, and chromaticity is related to the color aspects of light and how colors are perceived, none of which directly classify types of paper.