In "there will come soft rains," why does the author turn the house into a mechanical creature? a. to stress how well run the future will be b. to keep readers from realizing at the start that no humans are present c. to stress how scientific advances can create the perfect society d. to compare the present with the earlier, non-mechanical times

I think the correct answer is D. to compare the present with the earlier, non-mechanical times.

Letter A. is incorrect because the text brings us to the conclusion that Earth is not suitable for biological life anymore. There has been a nuclear war or something like that and the only things that "survived" are the mechanical ones like the haouse or the mice. Some animals are still alive but have miserable lives.

Letter B. is also incorrect because since the beggining we can observe that no humans live there anymore. The chores the mechanical house keeps doing make clear they are gone.

Letter C. states that scientific advances create the perfect society but despite these advances humans ruined an entire planet leaving no room for a society itself.

Letter D. is the correct answer because as the mechanical house keeps doing its chores, it shows us how people lived in the past. The kids played, the family had breakfast, the man mowed the lawn, etc. Now the times changed and nothing of that exists anymore.  

The correct answer is B. to keep readers from realizing at the start that no humans are present.

Indeed, Bradbury’s story is intended to warn readers that the inevitable consequence of an all-out nuclear war is the extinction of the human race. His story is inspired by the much earlier poem from American poetess Sarah Teasdale, who wrote the poem of the same title in the aftermath of World War I, which until then had been the most devastating conflict in the history of the world at that time.

Since the house is a mechanical entity; it stresses the fact that it was built by humans but since no humans are present anymore, their absence is all the more noticed and the, dramatic impact for readers is stronger and everlasting.