In the Early 1990s,glass Manufacturers Developed a Green Chemistry Solution

In the early 1990s,glass manufacturers developed a green chemistry solution to reducing NO emissions and energy consumption.This involved

A) reducing the temperature required to melt the glass.
B) using liquid rather than solid starting materials to make the glass.
C) substituting 100% oxygen for air in the large furnaces used to melt and reheat the glass.
D) melting the starting materials in the absence of air (in a vacuum) .