Historian: The central claim of the "end-of-history" theory is that history has reached its final stage of development. According to its adherents, democratic ideals have triumphed over their rivals, and history is effectively at an ideological end. But, this view fails to consider that it is impossible to stand outside all of history to judge whether history is really at an end. Which one of the following can be most reasonably inferred from the historian's statement? ['Ideological developments are the essential elements of history.', 'We can never know whether the end-of-history theory is true.', 'If we were at the end of history, we would automatically know whether the end-of-history theory is true.', 'Advocates of the end-of-history theory have too ideological an understanding of history.']