Automated external defibrillators (AEDs) can identify and treat life-threatening heart arrhythmias. AEDs can be found in high traffic areas such as sports stadiums, shopping malls, government office buildings, and airports. Once activated by being opened, the AED provides instructions about what to do, including feedback about electrode placement and a warning should shock be needed to restore the heart rhythm. In doing so, the AED most directly addresses _____.