The distinguishing characteristic of all electrolyte solutions is that

a) contain molecules.
b) conduct electricity.
c) react with other solutions.
d) always contain acids.
e) conduct heat.

Option (B) is the correct answer.

Explanation:

An electrolyte is defined as a solution in which solute particles completely dissociate into ions in a solvent.

For example, NaCl is an ionic compound and when it is added to water then NaCl will completely dissociate into sodium and chloride ions.  

Therefore, this solution will be able to conduct electricity due to the presence of ions between them.

Thus, we can conclude that distinguishing characteristic of all electrolyte solutions is that they conduct electricity.