The correct answer is B. Manganese.
Manganese is a chemical element with the symbol Mn and atomic number 25. It is a metal in the periodic table that is a member of the group of transition metals. Manganese is a silvery-white metal that is found in nature as the mineral pyrolusite. It is used in a variety of applications, including batteries, steel production, and fertilizer production.
The Sandur region of Karnataka is a major producer of manganese ore. The ore is mined from open-pit mines and then processed at a nearby processing plant. The manganese ore is then exported to other countries, where it is used in a variety of applications.
The other options are incorrect. Copper is a metal that is found in nature as the mineral chalcopyrite. It is used in a variety of applications, including electrical wiring, plumbing, and jewelry. Limestone is a sedimentary rock that is composed of calcium carbonate. It is used in a variety of applications, including construction, agriculture, and manufacturing. Gold is a precious metal that is found in nature as the mineral gold. It is used in a variety of applications, including jewelry, coins, and electronics.