Final answer:
Red glass is made by adding gold nanoparticles, which impart a red color. Chromium compounds give a green hue when combined with iron, and other compounds like cadmium sulfide can also create red glass.
Step-by-step explanation:
To create red glass, specific chemical compounds are added to the glass mixture to produce the desired color. The correct answer to how red glass can be made is by adding gold nanoparticles to the glass. While chromium compounds can indeed give a green hue when combined with iron(II) oxide, it is the gold nanoparticles that impart a red color to the glass.
Other compounds such as cadmium sulfide can also be used for creating red hues. In the past, uranium was used to make glass with a deep red or greenish-yellow color, famous as uranium glass. As for the other options listed in the question, silicon is the base component of glass but does not impart color, and lead compounds increase the refractive index and brilliance but do not provide a red color.