The correct answer is: Cement.
Limestone is a sedimentary rock composed mainly of calcium carbonate (CaCO3). It is the most common sedimentary rock on Earth, and it is used in a variety of industries, including cement, construction, and agriculture.
Cement is a binding agent that is used to make concrete. Concrete is a mixture of cement, water, and aggregates (sand and gravel). It is one of the most widely used building materials in the world.
Limestone is a major source of calcium carbonate, which is the main ingredient in cement. The limestone is crushed and then heated to a high temperature, which causes it to decompose into calcium oxide and carbon dioxide. The calcium oxide is then mixed with water to form calcium hydroxide, which is then mixed with clay and sand to form cement.
The limestone deposits in Manipur are significant for the production of cement. The state has a large reserve of limestone, and it is one of the major producers of cement in India. The cement industry in Manipur is a major contributor to the state’s economy.
The other options are incorrect because:
- Fertilizer is made from a variety of materials, including phosphate rock, potash, and nitrogen. Limestone is not a major source of any of these materials.
- Pharmaceuticals are made from a variety of materials, including plants, animals, and minerals. Limestone is not a major source of any of these materials.
- Construction materials are made from a variety of materials, including wood, steel, and concrete. Limestone is a major source of limestone, which is used in the production of concrete.