Answer:
The factors that must remain constant in the experiment are:
Temperature
Relative humidity
Light intensity
Usually in an experiment, the factor that is remained the same or are kept constant through out the period of the experiment are called the controlled variables or controlled factors.
Examples of such factors include:
Temperature
Relative humidity
Light intensity
Take for example, in an experiment to test for the effect of different fertilizers on the growth of a plant, the temperature, relative humidity and light intensity should be kept constant.
The temperature, relative humidity and light intensity here are the external factors that affects the outcome of an experiment and must be kept constant.
That is why is it essential that these factors be kept constant.
Explanation:
