Which technique does homer use at the beginning of book 9 of the odyssey to inform readers about ulysses’s adventures after the trojan war?
a)in medias res
b)foreshadowing
c)invoking the muse
d)flashback

The technique used is flashbacks.The reason is that Ulysses sits and tells about his travelling adventures.This makes the narration richer as it gives examples of the resources Homer has as a poet . At the  same time this technique  makes the Odyssey more interesting and attractive for its readers.

you can infer that to folke dude was spying for allied nations

i literally just read the book and studied it for months so i could you, but i need to know where these questions are coming from. they are too general.