The correct answer is A) Khammam.
Khammam is a district in the Indian state of Telangana. It is located in the south-western part of the state and is bordered by the districts of Warangal to the north, Nalgonda to the east, Karimnagar to the south, and Andhra Pradesh to the west. The district has a population of over 3.5 million people and is the second most populous district in Telangana.
The district is known for its graphite deposits. The graphite mines in Khammam are some of the largest in the world. The graphite is used in a variety of industries, including the manufacture of batteries, lubricants, and semiconductors.
The other options are incorrect. Warangal is known for its historical monuments, Mahabubnagar is known for its agriculture, and Rangareddy is known for its IT industry.