I think it's E.
to show how the consequences have changed or remained the same over time
Throughout history, authors tend to discuss similar topics. It might seem surprising that so many people at different points in time still find a topic relevant. However, there are reasons for authors to do it. For example, an author might find that the issue is not exacty the same as it was before. An author might also find that an issue is timeless, and therefore interests people at all times in history. Finally, an author might want to investigate how the treatment of the issue has changed over time.
