Respuesta :
The correct explanation is D.
Sodium being an Alkali Metal has a high tendency to lose its only valence electron to attain Neon configuration. In this process, it becomes positively charged, and hence becomes a Cation.
Chlorine is a non-metal that is one electron short of attaining Argon configuration, and hence readily takes the available electrons to become a negatively charged Anion. Since these two are oppositely charged, by the laws of electrostatics, they attract each other forming an Ionic Bond that requires considerable energy to break.