The correct answer is: d) All of the above.
Limestone is a sedimentary rock composed mainly of calcium carbonate. It is the most common type of rock in the world, and it is used in a variety of industries.
Cement production is one of the most important uses of limestone. Limestone is calcined (heated to a high temperature) to produce quicklime, which is then mixed with clay and sand to produce cement. Cement is a key ingredient in concrete, which is used in construction all over the world.
Iron and steel production is another important use of limestone. Limestone is used to remove impurities from iron ore, and it is also used to make limestone flux, which is used to lower the melting point of iron ore.
Construction is another major industry that uses limestone. Limestone is used in a variety of construction materials, including concrete, bricks, and tiles.
In conclusion, limestone is an important resource that is used in a variety of industries. It is a key ingredient in cement, iron and steel, and construction materials.