Given information:

A factor that is used to try to explain or predict a dependent variable is referred to as an independent variable in statistics and research.

Hence, option C. is correct.

Reason:

An independent variable is a variable that is not affected by any other variable and hence is named as an independent. But a slight change in the value of the independent variable changes the value of the dependent variable accordingly. Hence, it can be said that it explains or predicts the dependent variable.

Reasons for the wrong options:

Option A.

An empirical variable is a variable that arises from a particular realization of a sequence of random variables that is usually finite. It clearly shows there is no relation between an empirical variable with the dependent variable. Hence, this option turns out to be wrong.

Option B.

A skewed variable is a variable that describes the asymmetry of any symmetrical bell curve (normal distribution data set). If the curve is seen to be shifted towards left or right, then it is described as a skewed variable. It also clearly shows that there is no relation between this type of variable with the dependent variable. Hence, this option also turns out to be wrong.

Option D.

An effectual variable is a variable that measures the effect of any other variable. Hence, this option also turns out to be wrong.