B - I and II only
An author of a book and the purpose why he wrote a book can be better understood through both the actual details of a particular story, where we directly see what he wanted to say and what was the purpose of a specific topic, as well as the historical context in which the book was written in.
The publisher's life history has probably less relevant information regarding what an author, that he decided would publish under him, wanted to say with the book itself.