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 A
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
с
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