They are talking about B because no one knows what the future will be like. hope this helps! Everything other than b is not true becuase they are past events, the future has not happened.
When historians talk about the future, they are referring to events that have not yet occurred.
An important part of the historian's job is to study the past to understand what happened many years ago in order to forecast what could happen in the future. This way, knowing what provoked the events and incidents of the past, humans can be able to repeat the mistakes of the past and improve the chances for a better future.
