The correct answer is a) magnesite. Magnesite is a magnesium carbonate mineral that is used as a refractory material in the steel industry. It is also used in the manufacture of ceramics, glass, and other products.
Limestone is a sedimentary rock composed primarily of calcium carbonate. It is used in the manufacture of cement, lime, and other products.
Feldspar is a group of minerals that are used in the manufacture of glass, ceramics, and other products.
Bauxite is an aluminum ore that is used in the manufacture of aluminum.
Magnesite is the correct answer because it is a refractory material. Refractory materials are materials that can withstand high temperatures without melting or decomposing. They are used in a variety of industries, including the steel industry. In the steel industry, magnesite is used to line furnaces and other equipment that is exposed to high temperatures. It helps to protect the equipment from the heat and prevents it from corroding.
Limestone, feldspar, and bauxite are not refractory materials. Limestone is a sedimentary rock that is composed primarily of calcium carbonate. It is used in the manufacture of cement, lime, and other products. Feldspar is a group of minerals that are used in the manufacture of glass, ceramics, and other products. Bauxite is an aluminum ore that is used in the manufacture of aluminum.