Answer:
A scientific experiment should contain three variables:
1 Dependent variable: the variable which has to be studied in the experiment.
2 Independent variable: the variable which can be manipulated or gets changed in the experiment.
3. Control variable: the variable which is kept constant or the same throughout the experiment.
In the given question.
1. Independent variable is the type of laundry reagent.
2. Dependent variable- the clean cloth after washing.
3. Control variable- the amount of water, the temperature of the water and the amount of detergent.