Final answer:
The poem 'There Will Come Soft Rains' is set after a deadly and destructive human war, depicted by a thriving natural world that remains indifferent to human absence.
Step-by-step explanation:
The setting of the poem 'There Will Come Soft Rains' best corresponds to option B: The poem is set after a deadly and destructive war between humans. This is evident through lines that suggest a complete absence of human life and an indifference of nature to humanity's fate.
Specifically, lines such as 'And not one will know of the war, not one' and 'Would scarcely know that we were gone' imply that the natural world continues unfazed in the wake of human conflict. Detailed descriptions of the natural world thriving without human presence reinforce the theme that nature is enduring and indifferent to the wars of mankind.