Answer:
I feel it's to easily differentiate the positive from the negative...... like in gram staining of bacteria, the colour tell us which bacteria is gram positive or gram negative...... I just feel that this is science and it is advisable to know what the opposite result of an experiment should look like.
Whats the experiment? there's no experiment here
D. hormones would be the correct answer, which are chemical substances produced by gakbdd
