Answer:
(these are from the internet if you are doing an exam try to change the sentence structure )
Explanation:
What is Controls?
A controlled variable is a variable that could change but is intentionally kept constant in order to clearly show the relationship between dependent and independent variables. It is also a variable that is not of primary interest and hence constitutes a third factor whose influence is to be controlled or eliminated. These variables either need to be kept constant during the experiment or be monitored and recorded. This ensures that their influence can be assessed. Most experiments have more than one control.
An example used to explain control variable is the effect of fertilizers on a plants growth, whereby the growth of plants differs based on the amount of fertilizer used. The fertilizer, in this case, is the control variable.
Other examples include time, pressure and temperature.
