Concept:Diamond is used as an abrasive because of its extreme hardness.
Explanation:An abrasive tool works by rubbing against a surface to scratch or grind it away.
To be effective, the abrasive must be harder than the material it acts on.
Diamond is the hardest known natural substance on Earth.
Due to this hardness, diamond particles can easily cut, grind, and polish substances such as glass, stone, and metal.
The hardness of diamond gives it superior scratching and cutting power.
A high melting point does not itself make a material abrasive.
Its octahedral shape is an external feature and is not responsible for abrasive action.
Durability is also not the key property that makes diamond useful as an abrasive.
Therefore, hardness is the property that enables diamond to function as an abrasive.
Answer:B. hardness