Answer : Option A) Mass is the independent variable, and boiling point is the dependent variable.
Explanation : In the experiment of adding salt to the boiling water, the independent variable is the amount of salt added because it is not dependent on any other factor of the experiment. Whereas dependent variables is the boiling point of the water which changes on addition of salt, which means it is dependent on salt addition. Also, the constant variable is the amount of water which does not changes with anything and remains constant throughout the experiment.