The correct option is (c) AIN.
Formulas for network solids are simple ratios of the component atoms represented by a formula unit like those for ionic compounds.
Some examples of network solids are diamond with a continuous network of carbon atoms and silicon dioxide or quartz with a continuous three-dimensional network of SiO2 units. Graphite and mica group of silicate minerals structurally contains two dimensional sheets covalently bonded within the layer with other bond types holding the layers together whereas glasses are the disordered network solids. They are prepared by rapid cooling of melts so that little time is left for atomic ordering to happen.
