Answer:
If a solution conducts electricity, it is positive evidence that solute dissolved in solvent is electrolyte.
Because of the protons connected to the Nitrogen oxide group giving it its positive charge.
This question is incomplete. Luckily, I found the same problem which is shown in the attached picture. To answer the question, we must know how the size and charge affect the lattice energy. The answer is: lattice energy increases with the increasing charge of the ions, and decreasing radius of the atoms.
<em>Therefore, the ranking would be: A < B < C</em>.