The correct answer is A. Carbon black.
Carbon black is a fine black powder that is produced by incomplete combustion of hydrocarbons. It is used as a filler in rubber to improve its strength, durability, and resistance to wear and tear. It is also used in inks, paints, and plastics.
Coal is a solid fossil fuel formed from the remains of ancient plants and animals. It is used as a fuel for electricity generation, heating, and transportation.
Coke is a solid fuel produced from coal by heating it in the absence of air. It is used in blast furnaces to produce iron and steel.
Graphite is a form of carbon that is soft and flaky. It is used as a lubricant, a conductor of electricity, and a component of pencils.