Which words from paragraph 1 help the reader understand the experience of a newspaper carrier?

the rigid outer part of the earth, consisting of the crust and upper mantle is the lithosphere.     answer   crust and outer part of the mantle.

i believe it is the first choice (1.)

because the major theme is(“both the wild and civilization have rules.”)

and also as u said,( based on what buck learns within the call of the wild, "both the wild and civilization have rules".this is true of humans within society as well.