Answer: D-variable
Explanation:
A variable is the parameter over which changes can be made and observed so as to determine the outcome of the experiment. The two important variables such as dependent and independent variables and changes occurring over them can be useful in determining the outcome of the experiment.
An independent variable is the one which can be changed or manipulated by the experimenter so as to observe the impact of such change over the dependent variable. A dependent variable cannot be manipulated in the experiment instead the changes occurring in the dependent variable are because of the changes occurring in the independent variable. The observations on the dependent variable can be used for determining the outcome of the experiment.
