Final answer:
The Schachter-Singer two-factor theory of emotion describes emotions as a process where a physiological response is followed by a cognitive label, forming the emotional experience.
Step-by-step explanation:
When Ross explains the Schachter-Singer two-factor theory of emotion to his younger brother, he should describe it as a situation causing a physiological response that is followed by a cognitive label. This theory posits that for an emotion to be experienced, both physiological arousal and cognitive appraisal must occur. The correct answer to the question is a) physiological response that is followed by a cognitive label.
According to this theory, emotions are composed of two key factors: physiological arousal and cognitive appraisal. The physiological response is often a uniform reaction, such as an increase in heart rate, that is not distinctly tied to any specific emotion. It is the cognitive label, or interpretation of the situation, that shapes the actual emotional experience. This cognitive appraisal process is critical because, without it, the physiological response alone would not result in a differentiated emotional state.