<u>Answer:</u> The aluminium chloride solution will have the highest conductivity.
<u>Explanation:</u>
Conductivity is defined as the ability of a substance to conduct electricity.
When an ionic compound is dissolved in water, it dissociates into its respective ions.
As electricity is the flow of ions or electrons. So, an ionic compound will conduct electricity due to the presence of ions in the solution.
More number of ions dissociated in the solution, more amount of electricity will be conducted.
For the given options:
1) Copper (II) chloride
The chemical formula of the given compound is 
It will dissociate to form 1 mole of
ions and 2 moles of
ions
Total number of ions in the solution = 3
2) Aluminium chloride
The chemical formula of the given compound is 
It will dissociate to form 1 mole of
ions and 3 moles of
ions
Total number of ions in the solution = 4
3) Lithium chloride
The chemical formula of the given compound is LiCl
It will dissociate to form 1 mole of
ions and 1 mole of
ions
Total number of ions in the solution = 2
4) Calcium chloride
The chemical formula of the given compound is 
It will dissociate to form 1 mole of
ions and 2 moles of
ions
Total number of ions in the solution = 3
As, the number of ions is highest for aluminium chloride. So, it will have the highest conductivity.
Hence, the aluminium chloride solution will have the highest conductivity.