Which aspect of act 2 of "the monsters are due on maple street" marks it as science fiction and not fantasy fiction?

Read the passage from animal farm. one sunday morning squealer announced that the hens, who had just come in to lay again, must surrender their eggs. napoleon had accepted, through whymper, a contract for four hundred eggs a week. the price of these would pay for enough grain and meal to keep the farm going till summer came on and conditions were easier. when the hens heard this, they raised a terrible outcry. they had been warned earlier that this sacrifice might be necessary, but had not believed that it would really happen. they were just getting their clutches ready for the spring sitting, and they protested that to take the eggs away now was murder. for the first time since the expulsion of jones, there was something resembling a rebellion. led by three young black minorca pullets, the hens made a determined effort to thwart napoleon's wishes. their method was to fly up to the rafters and there lay their eggs, which smashed to pieces on the floor. napoleon acted swiftly and ruthlessly. he ordered the hens' rations to be stopped, and decreed that any animal giving so much as a grain of corn to a hen should be punished by death. the dogs saw to it that these orders were carried out. for five days the hens held out, then they capitulated and went back to their nesting boxes. nine hens had died in the meantime. their bodies were buried in the orchard, and it was given out that they had died of coccidiosis. whymper heard nothing of this affair, and the eggs were duly delivered, a grocer's van driving up to the farm once a week to take them away. which detail from the passage supports the claim that this is an allegory for the great purge? the hens holding out for five days but capitulating the eggs being delivered to the grocer the protesting hens being intentionally starved coccidiosis spreading on the farm