Passage Summary: Professor Burns thinks an old discovery of a comet reservoir was a mistake because new attempts to see it failed. Dr. Khan points out that those new attempts were made during bad viewing conditions.

Reasoning: Professor Burns argues that a lack of confirmation in recent observations proves earlier sightings of a comet reservoir were wrong, but Dr. Khan notes those recent observations were conducted under poor conditions.

Analysis: Dr. Khan is undermining the weight of the 'nonconfirmation' by attacking the quality of the recent data. If the recent observations were done under poor conditions, their failure to see the reservoir doesn't necessarily mean the reservoir isn't there; it might just mean the conditions weren't good enough to spot it. We should look for an answer that suggests the recent observations are not a definitive reason to reject the earlier ones. The facts suggest that Professor Burns's conclusion is premature or lacks sufficient evidence.