C. It highlights how greed caused humans' values to drastically change over time.
Structuring the poem in "ages" allows the poet to illustrate the evolution of human values and behaviors over time, particularly in relation to nature and greed. Each age can represent a different mentality or societal shift, emphasizing how greed has influenced humanity's actions and its repercussions on the world. By using this structure, the poet can effectively convey a message about the progression and impact of these changes throughout history.