Final answer:
Ionic compounds d. arrange their atoms in repeating patterns within a crystalline lattice due to the strong electrostatic forces of ionic bonds, making them hard, brittle, and high melting point substances that are conductive when dissolved or melted.
Step-by-step explanation:
The property of ionic compounds described in the student's question is that d. atoms arrange themselves in repeating patterns. This is due to the fact that ionic compounds form a crystalline lattice structure with orderly repeating patterns, which is a manifestation of the strong electrostatic forces that hold the ions together.
These ionic bonds result in some characteristic properties of ionic compounds which include being hard and brittle, having high melting and boiling points, poor conductivity in the solid state, and being good conductors of electricity when dissolved in water or melted.