The correct answer is: b) Limestone.
Limestone is a sedimentary rock composed mainly of calcium carbonate (CaCO3). It is the most common type of limestone in the world and is used in a variety of industries, including the cement industry. Limestone is used in cement production because it is a source of calcium oxide (CaO), which is one of the main ingredients in cement.
Granite is an igneous rock composed mainly of quartz, feldspar, and mica. It is a hard and durable rock that is used in a variety of construction applications, including building foundations, countertops, and monuments. Granite is not used in the cement industry because it is not a source of calcium oxide.
Iron ore is a mineral that contains iron. It is used in the production of iron and steel. Iron ore is not used in the cement industry because it is not a source of calcium oxide.
Bauxite is an ore of aluminum. It is used in the production of aluminum. Bauxite is not used in the cement industry because it is not a source of calcium oxide.