Choice A is the best answer. The convention being tested is the use of plural and possessive nouns. The plural possessive noun “people’s” and the plural noun “stories” correctly indicate that there are multiple stories from multiple people.
Choice B is incorrect because the context requires the plural possessive noun “people’s” and the plural noun “stories,” not the plural noun “peoples” and the singular possessive noun “story’s.” Choice C is incorrect because the context requires the plural possessive noun “people’s,” not the plural noun “peoples.” Choice D is incorrect because the context requires the plural noun “stories,” not the singular possessive noun “story’s.”