Read the excerpt from "how the grimm brothers saved the fairy tale"

all of the tales in the first edition bear the marks of their diverse storytellers who believed in the magic, superstitions, and miraculous transformations of the tales. it may be difficult for us to understand why this is the case, but for the storytellers and writers of these tales, the stories contained truths about the living conditions of their times. the tales in the first edition were collected not from peasants, as is commonly believed, but mainly from literate people whom the grimms came to know quite well. evidence shows that these people often obtained their tales from illiterate or anonymous informants. even if they did not know their informants, the grimms came to trust almost everyone who contributed to their collection. it is this mutual trust that marks the tales as something special and endows them with a certain humanity, what germans call menschlichkeit, and it is this mutual trust among folklorists in the nineteenth century that marks it as the golden age of folk and fairy tales. the tales in the first edition set a certain standard that collectors began to follow and still follow even today.

which idea does the author use to conclude the paragraph?
the grimms trusted their contributors to give them tales that came from the oral tradition of the culture.
storytellers believed in the magical, life-saving transformations they reported in their folk tales.
the first-edition tales influenced folklorists to trust one another to gather authentic tales of living conditions.
literate people collected the first-edition tales and gave them to the grimm brothers.