Answer:
c.) gypsum board
Step-by-step explanation:
Exterior sheathing for noncombustible light gauge steel walls is typically made of gypsum board. Gypsum board is a type of interior wall and ceiling finish that is made of gypsum, a soft mineral that is found naturally in the earth. Gypsum board is commonly used as exterior sheathing for noncombustible light gauge steel walls because it is lightweight, easy to install, and provides a smooth finish that is ready for paint or wallpaper. Other materials that may be used as exterior sheathing for noncombustible light gauge steel walls include plywood, OSB (oriented strand board), and sheet metal, but gypsum board is the most common choice.