The correct answer is answer C ("The article will be biased because the historian is using only one source about the ruler").
If a historian only took this one scroll to write a biography on its subject (the ruler), it would most likely be extremely misleading and inaccurate. There's no way of getting closer to the truth of any subject without contrasting a variety of opinions from different sources. What if people working for this ruler wrote it in a way that made him look good? What if it was written under pressure? What if it was a complete lie? These and many other questions should come to mind as possible ways in which relying on one source might compromise historical facts.
