Why is sodium chloride a compound but not a molecule? i thought all the compounds are molecule but not all molecules are so confusing.?

Molecule is the general term used to describe any atoms that are connected by chemical bonds. Every combination of atoms is a molecule. A compound is a molecule made of atoms from different elements.
Well, if a molecule is considered to be a discrete small unit made up of atoms joined together, then NaCl, and any other ionic solid is not really a molecule. In NaCl we have a repetitive crystal structure in which each Na+ ion is surrounded by Cl- ions, and vice-versa, for as far as the crystal extends. There really isn't such a thing as an NaCl molecule.

The answer for this question is d. none of these

They are all full and don't need any more electrons in there outer shell.