d
A network solid or covalent network solid is a chemical compound (or element) in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material.

In a network solid there are no individual molecules, and the entire crystal may be considered a macromolecule.

So in Diamond, \(\mathrm{SiO}_{2}\) atoms are bonded by covalent bonds in a continuous network extending throughout the material.

In a network solid there are no individual molecules, and the entire crystal may be considered a macromolecule.

Hence option D is correct.