Both stories praise the ideal of family and express idea of inportance of a family in people's lifes and. So, The authors of Desert Exile and The Way to Rainy Mountain both express idea C. Family is more important than country. Problem of family vs country is very common, and those authors develop it during the whole story.
The correct answer is EXTENDED METAPHOR.
Extended metaphor refers to a comparison between two things that are not alike, which continues throughout a series of sentences in a paragraph or in lines of poem. It is also called sustained metaphor and authors usually use it in order to create a clear comparison between two things.