The answer is the first one.
In "Writers often disavow the notion of a 'literary duty'" the author conveys a somewhat condescending attitude, as if they would always follow this and set aside anyone who said otherwise. This attitude says the author is looking down on them, and that the author believes that many authors do not meet their standards.
Another answer I would consider is "...writers ruined by their shrill commitments." However, there is no context or clear tone. The author could be mournful of the lost potential for all we know.
Option a. the beginning of a story, when the characters are introduced
Exposition is the insertion of the important background within a story. It is the process of scattering information through the text. Incluing is a technique in which the reader is gradually exposed to background information about the world in which the story is set. The idea is to clue the readers into the world the author is building them without being aware of it.
