A. RGB
B. HЕX
C. Material Design colors
D. CMYK

Solution

C. Material Design colors

Explanation

<p>W3.CSS includes a built-in color library that is primarily based on Google's Material Design color palette. <br>It provides predefined color classes such as:</p><ul><li>&nbsp;w3-red</li><li>w3-blue</li><li>w3-green</li><li><span style="font-size: 1rem; letter-spacing: 0.01rem;">w3-indigo</span></li><li><span style="font-size: 1rem; letter-spacing: 0.01rem;">w3-teal</span></li></ul>