Passage Summary: A monk in England saw big sunspots, and five days later, people in Korea saw the northern lights. Since these two events usually happen five days apart, the second event suggests the first one really happened.

Conclusion: The Korean aurora sighting supports the validity of John of Worcester's sunspot observation.

Reasoning: There is a documented five-day average gap between sunspots and auroras, which matches the timing between John's report and the Korean event.

Analysis: To strengthen this argument, we need to bolster the link between these two specific events. The argument assumes that the aurora in Korea wasn't just a coincidence or caused by some other sunspot activity. Look for an answer that suggests auroras were rare in that region or that no other sunspots were reported around that time that could have caused the Korean sighting.