Blank is the natural difference between members of a species?

Answer and Explanation: Differences between members of the same species are called genetic variations. ... Each member of the species will have a slightly different combination of alleles thanks to genetic variation. Genetic variation is what makes individual humans so unique, even though we all belong to the same species.

d. new methods of assembly are introduced.

explanation:

this allows for the goods to be made on a larger scale. not faster because now it is shown to be made better, hence the greater productivity in the question. it is calling for something new to be introduced.

brave new world, aldous huxley (1932)