Final answer:
In the poem by Sara Teasdale, the blame for the apocalypse is likely attributed to humanity's role in the destruction of the world.
Step-by-step explanation:
In the poem by Sara Teasdale, the blame for the apocalypse is not explicitly stated. However, based on the provided references and information, it can be inferred that the poem explores the idea of humanity's role in the destruction of the world.
The lines 'about the long-term relationship of humans to this planet' and 'we lay waste our powers; Little we see in Nature that is ours' suggest that humans are responsible for the destruction and neglect of nature.
Therefore, option 2) Humanity is likely to be the answer.