Since this type of scientific method will utilize experimentation, the two varibles that would be part of the procedure is the different detergents, thus can specifically be the content, amount and acting agent as the covariables of the independent variable, detergents. And the other is the cotton fabric as the dependent variable.
The two varibles that aren't involve is the color of the cotton fabric since the experiment has not specified any but clearly specifies cotton fabric and the other will be other types of fabric.
But what is the problem? Maybe then i could answer your question.
The answer is A
hope this helps
