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 manufacture of other products, such as paper, glass, and chemicals.
The districts of Kadapa and Kurnool in Andhra Pradesh are known for their limestone deposits. These deposits are of high quality and are used to produce cement and other products. The limestone industry in these districts is an important source of employment and revenue.
The other options are incorrect because they do not contain districts that are known for their limestone deposits.