Passage Summary: This weed-killer has two versions, but only one actually works; because soil changes which version is present, we can't trust the general test results.

Conclusion: Current data regarding the effectiveness of this specific weed-killer is likely unreliable.

Reasoning: The chemical exists in two forms, only one of which is effective, and the ratio of these forms changes significantly based on local soil conditions.

Analysis: The chemist is pointing out a variable—the concentration of the active versus inactive molecule—that fluctuates based on the environment. To strengthen the claim that the data is misleading, we need to find an answer that suggests this variable was not controlled or accounted for during testing. Look for information indicating that researchers didn't know which form of the molecule was present in their samples.