The correct answer is A. Silicon carbide.
Carborundum is a trade name for silicon carbide, a very hard, abrasive material. It is used in a variety of applications, including grinding wheels, cutting tools, and abrasive papers. Silicon carbide is a compound of silicon and carbon, and it is typically produced by heating silica sand and coke in an electric furnace.
Silicon oxide is a different compound, also known as silica. It is a common mineral that is found in sand and quartz. Silicon oxide is not as hard as silicon carbide, and it is not used as an abrasive.
Calcium carbide is a compound of calcium and carbon. It is a white, solid that is used to produce acetylene gas. Calcium carbide is not used as an abrasive.
Calcium oxide is a compound of calcium and oxygen. It is also known as lime or quicklime. Calcium oxide is a white, solid that is used in a variety of applications, including construction, agriculture, and water treatment. Calcium oxide is not used as an abrasive.