In modern biology, there are three approaches to classifying organisms: systematics, cladistics and molecular evolutionary taxonomy. They are all based on organisms' relation to each other, but use different indicators to assign the degree of relationship
What exactly is the question you are asking?
A. Sugar... Because the others are mixes of things and combinations. Sugar is pure and on its own.
I hope this helps!
C, to make sure the design works as expected.
A prototype is first, typical model of the said product. Hope this helps!