Aqueous solution of which of the following compounds is the best conductor of electric current?

• A

  Hydrochloric acid, HCl

• B

  $\text{ Ammonia, }{\mathrm{NH}}_3$

• C

  $\text{ Fructose, }{\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$

• D

  $\text{ Acetic acid, }{\mathrm{C}}_2{\mathrm{H}}_4{\mathrm{O}}_2$