A lubricant is a substance that helps to reduce friction/heat/wear and tear when introduced to solid surfaces.
Graphite is used as a lubricant since ancient times.
The graphite has a layered structure that is held together by weak van der Waal forces. As it is easy to break van der Waal forces thus the layers slide on one another. Due to this slippery nature, graphite is used as a lubricant.
The layered structure of graphite is shown below:
Explanation for incorrect options:
A. Coke is an almost pure form of carbon it cannot work as a lubricant.
B.Diamond is composed of the single element carbon, and it is the arrangement of the C atoms in the lattice, it does not work as a lubricant.
D.Charcoal is a fine black powder or black porous solid consisting of carbon it does not work as a lubricant.
