Final answer:
The property of an ionic compound is c) Crystal shape, due to its crystalline structure and the ionic bonds that hold the cations and anions together.
Step-by-step explanation:
The property of an ionic compound that the question refers to is c) Crystal shape. Ionic compounds, or salts, are characterized by a crystalline structure where cations and anions are held together in a regular spatial arrangement by ionic bonds. These compounds exhibit several key properties due to the strong electrostatic forces between the oppositely charged ions. Notably, they have high melting and boiling points and are also brittle in nature. Additionally, ionic compounds are poor conductors of electricity when solid but become good conductors once dissolved in water or melted, due to the free movement of the ions.