Step 1: Understanding the Concept:
Stress is a physiological and psychological response to demands or threats, characterized by a state of heightened arousal (the "fight-or-flight" response). The question asks for the term that describes the opposite state.
Step 2: Detailed Explanation:
(A) Relaxation: The relaxation response is the physiological opposite of the stress response. It is a state of deep rest that is characterized by decreased heart rate, blood pressure, and muscle tension. It is associated with the parasympathetic nervous system (the "rest and digest" system).
(B) Conditioning: This is a process of learning associations between stimuli and behaviors (e.g., classical and operant conditioning). It is a learning mechanism, not a state of arousal.
(C) Thinking: This is a general cognitive process. While stressful thoughts can induce stress and calm thoughts can induce relaxation, thinking itself is not the opposite state of stress.
Step 3: Final Answer:
The physiological and psychological state opposite to stress is relaxation.