Step 1: Understanding the Concept:
An emotion is a complex psychological state that involves subjective experience, physiological response, and behavioral/expressive response.
Step 2: Detailed Explanation:
Emotions are typically triggered by specific internal or external events.
They serve an evolutionary purpose by preparing the body for action (e.g., the "fight or flight" response triggered by fear).
Option (b) describes a mood (longer duration, no specific cause).
Option (c) describes only the cognitive aspect, ignoring the physiological and behavioral components.
Step 3: Final Answer:
Emotions are functional responses to stimuli that drive specific behaviors for adaptation.