According to the Yerkes-Dodson Law, how does a controller's level of stress or arousal affect their performance?

1. Performance is optimal at moderate levels of stress; both extremely low stress (under-arousal) and extremely high stress (overload) degrade performance.
2. Performance increases linearly with stress; the more pressure applied, the more accurate the controller becomes.
3. Performance is completely unaffected by stress, as professional training overrides physiological arousal.
4. Performance is highest at zero stress, and declines steadily as any stress is introduced.