In Demonstrations of Strong and Weak Electrolytes and Nonelectrolytes,a Lightbulb

In demonstrations of strong and weak electrolytes and nonelectrolytes,a lightbulb apparatus that shows how much a solution conducts electricity by the brightness of the light is often used.When pure water is tested,the bulb does not light.Which one of the following aqueous solutions causes the bulb to burn the brightest?

A) formic acid,HCOOH
B) ammonia,NH₃
C) table sugar,C₁₂H₂₂O₁₁
D) a calcium salt,CaCl₂
E) methanol,CH₃OH