The correct answer is D.
A strong base is a substance that completely dissociates into its ions in water, producing a high concentration of hydroxide ions (OH-). Similarly, a weak base is a substance that only partially dissociates into its ions in water, producing a low concentration of hydroxide ions (OH-).
The term that completes the analogy is "Weak electrolyte", which is a substance that only partially dissociates into its ions in water and conducts electricity poorly. A strong electrolyte, on the other hand, is a substance that completely dissociates into its ions in water and conducts electricity well.
Therefore, the analogy can be completed as follows:
"Strong base is to weak base as strong electrolyte is to weak electrolyte."
I hope it helped you :)