Answer: Option (a) is the correct answer.
Step-by-step explanation:
Ionic compounds are the compounds whose atoms are combined together by transfer of electrons.
An ionic compound has partial positive charge on the cation and partial negative charge on anion.
For example, NaCl is an ionic compound whose atoms are arranged orderly due to the opposite charges on its atoms.
So, an ionic compound forms a neutral compound but not a neutral element.
Thus, we can conclude that ionic compounds form crystal structures.