A is the answer hope i helped
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Oh well Thx that could really help
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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.
Answer: Really hope this helps you.
Explanation: it depends in what you are using it for if you are using it for math then it means a relation from a set of inputs to a set of possible outputs where the input and the output is related exactly.