The correct answer is A) Readers can identify with the narrator, making the issue of slavery less abstract.
The other options of the question were B) The novel’s length allows more space to describe the horrors of slavery in-depth and from multiple angles. C) Audiences at the time had more of a taste for novels and longer works than short polemical works in newspapers.
D) Novels were kept in libraries where everyone could read them whereas newspapers were only available to subscribers.
Narratives like Equiano's autobiography were more effective in their indictment of slavery than shorter political or polemical works on the same topic in that readers can identify with the narrator, making the issue of slavery less abstract.
That is the case of former slave Olaudah Equiano (1745-1797), who was an African American who supported abolitionism and that later became a writer and wrote his autobiography in 1789 called "The Interesting Narrative of the Live of Olaudah Equiano." The way he wrote his biography using the figure of a narrator helps readers to understand the story and identify with the things the narrator is saying to make it more vivid.