We would need more information, are you sure this is all there is?
With the information that is given I believe that the answer is:
C. Constantly changing pieces of literature.
C. The rest are letters to people in familiar situations.
Answer:
Happily delivered
Explanation:
This is because they won't be happy but, terribly miserable because they can't do the work or even get any.
D. "his sister, who had taken a sales job, learned shorthand and French in the evenings so that she might be able to get a better position later on"
