D. Americans today spend over $100 billion more on fast food than they did in 1970.
This sentence is saying the same thing as "In 1970, Americans spent about $6 billion on fast food; in 2001, they spent more than $110 billion," just in a different way, which is referred to as paraphrasing.
There are five features of the emerging adulthood:
-the age of identity explorations;
-the age of instability;
-the self-focused age;
-the age of feeling in-between; and
-the age of possibilities.
Berta is clearly experiencing the instability one given that she can't enjoy neither her life at home nor her worklife. She is going through the instability which, in turn, will bring the self-focused one where she will find herself and what does she want.