prompt #2-

     I think that when Ray says that the land is an exchange she means that every thing is exchanged . Like in the chapter "Built By Fire" are helping each other because they depend on each other. So they need to exchange things to help the other stay alive. This is an example of an commensalism. this is because both things benefit from the exchange and they don't die because they didn't have the exchange. Another example of this would be a person giving another person some money for food.