The correct answer is: b) Limestone.
Limestone is a sedimentary rock composed mainly of calcium carbonate (CaCO3). It is the most common type of rock found in the Earth’s crust and is used in a variety of industries, including the cement industry.
Gypsum is a mineral composed of calcium sulfate dihydrate (CaSO4·2H2O). It is used in a variety of industries, including the construction industry, the paper industry, and the agricultural industry.
Bauxite is an aluminum ore that is used to produce aluminum metal. It is the most important aluminum ore in the world.
Bentonite is a clay mineral that is used in a variety of industries, including the construction industry, the oil and gas industry, and the agricultural industry.
Limestone is the correct answer because it is the most common type of rock found in the Earth’s crust and is used in a variety of industries, including the cement industry.