Which of the following exists as covalent crystals in the solid state?

1. Silicon ($\text{Si}$): Exists as a network covalent solid (similar to diamond).2. Sulphur (${\text{S}}_8$): Molecular solid.3. Phosphorous (${\text{P}}_4$): Molecular solid.4. Iodine (${\text{I}}_2$): Molecular solid.