Concept: During soap making, concentrated sodium chloride solution reduces soap solubility so it separates from the mixture.
Explanation:The soap formed remains dissolved in the reaction mixture.
Adding concentrated sodium chloride solution lowers the solubility of the soap.
This causes the soap to precipitate or float out of the solution.
This process is called "salting out".
It does not increase solubility, saponify, or emulsify the soap.
Therefore, options A, C, and D are incorrect.
The correct choice is the one that states the solubility of soap is decreased.
Answer: B — decrease the solubility of the soap.