What is the difference between sodium atom and a sodium ion

Pretty much any element(in your case sodium) contain these properties.

Atoms can be an ion, but not all ions are atoms. The difference between an atom and an ion has to do with net electrical charge. An ion is a particle or collection of particles with a net positive or negative charge. ... A stable atom contains the same number of electrons as protons and no net charge

It should be d if not then c