Which of the following most logically completes the argument given? Researchers studying the pathogen responsible for Chagas disease have created a medication that marks a significant advancement toward their objective of finding a cure that can eradicate the pathogen from the bloodstream of affected individuals. After patients infected with the pathogen underwent a full treatment regimen with the medication, no pathogen was detected in their blood. The researchers cannot yet assert that their objective has been met, however, since __________.