Final answer:
The therapist used Rational Emotive Behavior Therapy (REBT) to teach Carol to laugh at self-defeating ways of thinking.
Step-by-step explanation:
The therapist used a technique called Rational Emotive Behavior Therapy (REBT) to teach Carol to laugh at self-defeating ways of thinking. REBT encourages individuals to challenge and change irrational thoughts and beliefs that contribute to negative emotions and behaviors. By using humor and laughter, Carol can gain a new perspective and find it easier to let go of self-defeating thoughts.