I would say C is the most correct.
In D it depends on what water source you're using. Let's say it is a waterfall, then the source of the water (melting ice or a lake) may disappear in the future.
If you're using underwater "windmills" placed in the ocean, then you would expect it to last a while as the ocean will not disappear in the near future.
There are 3 moles of

<span>per 1 mole of salt and 1 mole of

</span>per mole of salt, the total ionic concentrations must be

of

, and

of
Answer: D) It conducts electricity when it is dissolved in water