Final answer:
Physiological arousal, as explained by the James-Lange theory of emotion, causes changes in heart rate, breathing, dilated pupils, and dry mouth when a person experiences an emotion.
Step-by-step explanation:
According to the James-Lange theory of emotion, physiological arousal is responsible for changes in heart rate, breathing, dilated pupils, and dry mouth when a person experiences an emotion. This theory suggests that the arousal comes first and then the emotional experience follows. For example, if a person encounters a venomous snake, their sympathetic nervous system would initiate physiological arousal, causing their heart rate to increase and their breathing to change. The person would then experience fear as a result of this physiological arousal.