The degree of lightness or darkness of a material is called value. To arrive at this answer, you can use your knowledge of color theory or conduct a search on the topic. In color theory, value refers to the scale from black to white, representing the lightness or darkness of a color. It is an important component of color along with hue (the type of color) and saturation (the intensity or purity of a color). Therefore, the correct answer is option C: value.
