Answer:
To help reader connect the work with events from the past
To make the text more realistic.
Explanation:
The authors use historical background in non-fiction to make the text appear realistic and helps readers to connect the work and events from the past.
Historical background can be defined as a memory, characters, events, etc that has happened or taken place somewhere in the past. The author's, in non-fictional works, use historical context to make their text more realistic. This also helps the readers to make inference of historical context with the works.
Therefore, option B and D are correct.