Correct Option: A

Dolomite a sedimentary rock resembling limestone but consisting principally of the mineral dolomite. It is an important source of magnesium and its compounds, and is used as a building material and refractory. Dolomite is used as an ornamental stone, a concrete aggregate, a source of magnesium oxide and in the Pidgeon process for the production of magnesium. It is an important petroleum reservoir rock, and serves as the host rock for large stratabound Mississippi Valley-Type (MVT) ore deposits of base metals such as lead, zinc, and copper. Where calcite limestone is uncommon or too costly, dolomite is sometimes used in its place as a flux for the smelting of iron and steel. Large quantities of processed dolomite are used in the production of float glass.