Passage Summary: A researcher defends her decision to hide data by claiming the experiment was botched because the chemicals used were too acidic.

Conclusion: The negative test results were scientifically invalid and did not warrant reporting.

Reasoning: The anthropologist claims the test was performed in an acidic solution, which compromised the accuracy of the results.

Analysis: The anthropologist's defense relies entirely on the idea that acidity ruins the test for toxin T. To strengthen this counterargument, we need evidence that confirms this chemical relationship. Look for an answer choice that provides a technical reason why an acidic environment would produce a false negative—perhaps by breaking down the toxin or interfering with the chemical markers the test is designed to detect. We want to turn her 'excuse' into a scientific fact.