Answer:
B. Pure water.
Step-by-step explanation:
You can see on the scale of pH, that downward is the most acids and upwards is the most alkaline (bases).
Lemon juice and vinegar would be acids with different pH, meaning that they have different H+ concentrations.
Sea water is a base near the neutral pH.
And pure water has a neutral pH, indicating that it can be a weak base or a weak acid too.
The answer would be pure water.