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 toexplain why some people are seen as great starting from birthexplain why some people are seen as great starting from birthshow that it is unremarkable if a few people achieve more than expectedshow that it is unremarkable if a few people achieve more than expectedlimit the author’s earlier remarks about greatness to a certain subset of peoplelimit the author’s earlier remarks about greatness to a certain subset of peoplechallenge the audience’s likely belief that the world is inherently fairchallenge the audience’s likely belief that the world is inherently fairreinforce the author’s overarching claim about ordinary people’s capacity for success