N“the raven and the first men: the beginnings of the haida,” which evidence best the reader infer that the haida might find it acceptable behavior to play tricks on one another?

The correct answer here is that the tricks in the story are told in a matter-of-fact manner.

In the story the Raven is shown playing tricks on the Sky-Chief and those tricks are described in such a way that we see that those are normal things. The matter-of-fact manner clearly shows this as it just shows the tricks without exaggeration or any type of a comment. They are just normal part of their lives. 

Astonishing means surprising