Answer: Solution (C) is the correct answer.
Step-by-step explanation:
A solution that is able to conduct electricity must contains almost similar number of positive and negative ions. This is because movement of these ions help in the flow of electric current from one point to another.
Hence, solution C will be able to conduct current effectively.
Whereas neutral particles does not participate in the flow of current moreover , when they collide with charged particles they cause hindrance in the path of current. As a result, current is not able to flow effectively. Hence, solution B will not be the best conductor of electricity.
On the other hand, solution A contains only neutral particles. Thus, there will be no flow of electric current at all.
Thus, we can conclude that solution C will be the best conductor of electricity.