The correct answer is: a) Kadapa and Kurnool.
Limestone is a sedimentary rock composed mainly of calcium carbonate (CaCO3). It is the most common sedimentary rock on Earth, and is found in significant deposits in many parts of the world. Limestone is an important mineral for the cement industry, as it is the main source of calcium carbonate. It is also used in the production of lime, paper, glass, and other products.
The districts of Kadapa and Kurnool in Andhra Pradesh are known for their large deposits of limestone. These deposits are of high quality and are suitable for use in the cement industry. The limestone in these districts is quarried and then transported to cement plants, where it is crushed and ground into a powder. The powder is then mixed with other ingredients, such as clay and sand, to form cement.
The cement industry is a major employer in Andhra Pradesh. The limestone deposits in the districts of Kadapa and Kurnool are a valuable resource for the state, and they contribute significantly to the economy.
The other options are incorrect because they do not contain districts where limestone is found in significant deposits.