Respuesta :
Answer:
Option (C)
Explanation:
The hardness of any material depends upon the type of chemical bonds and the energy requires to break that bond. Diamond and graphite has covalent bonding between their carbon atoms.
Gary rubs the diamond the graphite piece is scratched because diamond has strong covalent bonding then graphite. The bond energy of diamond is much higher than graphite. Gary rubs the piece of graphite against diamond, diamond doesn't scratch because diamond is harder than graphite.
Thus, the correct answer is option (C).