The correct answer is: a) Cement.
Limestone is a sedimentary rock composed mainly of calcium carbonate (CaCO3). It is the main raw material used in the production of cement, which is a key ingredient in concrete. Concrete is a versatile building material that is used in a wide range of applications, including construction, infrastructure, and manufacturing.
Andhra Pradesh is a state in southern India that has significant limestone deposits. These deposits have led to the development of a significant cement industry in the state. The cement industry is a major contributor to the economy of Andhra Pradesh and employs a large number of people.
The other options are incorrect because they are not directly related to limestone. Steel is made from iron ore, fertilizer is made from natural resources such as phosphate rock and potash, and glass is made from sand.