For Question 15, the option that describes an interaction in a text you might analyze is:
the effect that one person, thing, event, or idea has on another.
This option reflects the kinds of interactions you might explore, such as how the reintroduction of wolves affected the elk population in Yellowstone National Park.
For Question 17, if you have a specific question regarding the paragraph about Yellowstone National Park, please let me know, and I'll be happy to assist you!