Solids have properties like rigidity a definite shape and a define volume. If intermolecular forces are greater than thermal energy, substances exist as solid. Solids can be classified into two types. Crystalline solids and amorphous solids, Crystalline solids have regular arrangement of particles, definite geometric shapes, sharp melting points and definite heat of fusion. They are anisotropic and undergo clean cleavage. On the other hand, amorphous solid have no regular arrangement of particles, irregular shapes, melt over a range of temperature, no definite heat of fusion. They are isotropic and undergo irregular cleavage.
Solid X is very hard, electrical insulator in solid as well as molten state and melts at extremely high temperature. Name the type of solid is it?

Options

A. lonic
B. Metallic
C. Covalent
D. Molecular