In the context of the passage as a whole, the author's comparison between the qualities of people and of metals (paragraphs 5-6) primarily serves to А
explain why some people are seen as great starting from birth

B
show that it is unremarkable if a few people achieve more than expected
limit the author's earlier remarks about greatness to a certain subset of people

D
challenge the audience's likely belief that the world is inherently fair

E
reinforce the author's overarching claim about ordinary people's capacity for success