Final answer:
The Two-factor theory of emotion explains our conclusion of feeling nervous when we forget that we had strong coffee.
Step-by-step explanation:
The theory that explains our conclusion that we must be nervous because we feel shaky - while forgetting we just had two cups of strong coffee is the Two-factor theory of emotion. According to this theory, our emotions are composed of two factors: physiological arousal and cognitive interpretation. In this scenario, the physiological arousal from the strong coffee is misattributed as nervousness due to cognitive interpretation.