Which variable is being tested in this experiment?

Also know, which variable is tested in an experiment?

independent variable

Secondly, what type of a variable is an experimental control? In a controlled experiment, an independent variable (the cause) is systematically manipulated and the dependent variable (the effect) is measured; any extraneous variables are controlled.

Moreover, what is the test variable?

In statistical theory, a tested variable can be viewed as dependent variable which is the centre of random experiment. The dependent variables refer to that type of variable that measures the affect of the independent variable(s) on the test units.

How do you know if a variable is independent?

You can tell if two random variables are independent by looking at their individual probabilities. If those probabilities don't change when the events meet, then those variables are independent. Another way of saying this is that if the two variables are correlated, then they are not independent.