The correct options are
A C5H5N
D NH3
The base NH3 when gets dissolved in water dissociates into the ions NH+4 and OH−. Sometimes NH3 when dissolved in water forms the ions NH−2 and H+. At times NH3 does not react with water at all. Hence, NH3 does not dissociate completely into its ions when dissolved in water and thus NH3 is a weak electrolyte.
Similarly, when pyridine that is C5H5N is dissolved in water it forms the ions C5H6N+ and OH−. Thus pyridine too does not undergo complete dissociation into its ions. Hence it is a weak electrolyte
But KOH undergoes complete dissociation into its ions K+ and OH− ions when dissolved in water. Thus KOH is a strong electrolyte.