The biological basis for assigning all human beings into a singe species is that there so many, even tons of living organisms living on earth. These organisms differ in their external and internal organs and so to differentiate them from them, they are being classified into kingdoms then classes then phylums then family.
The answer for your question is A.
Because everything scientists do or see is put out where the whole world can see. But if they don’t do it accurately then they get proved wrong or even lose their job. And the more accurate an answer is the more opportunity they have to venture and see more Han what they already know.
