Answer:
Humans living in or near the town.
Step-by-step explanation:
Rachel Carson's short fairytale "A Fable For Tomorrow" is one of her collection of stories in her book "Silent Spring". This fable pictures a town full of life that suddenly changes to a deserted town after numerous maladies and illnesses overtook it.
Though the story started off with a quaint, nice, and peaceful town, it slowly progresses into a deserted, imaginary town. This was because of the "a white granular powder [that] had fallen like snow upon the roofs and the lawns, the fields, and streams." Though Carson admits in the end that this is no real story of any town, in particular, it still can be a possibility in many parts of America. And the source of this "white powder" is, as Carson wants to point out, the frequent use of pesticides and chemicals by humans.
Thus, the correct answer is the last option.