Leanne is being treated for depression after a breakup with her boyfriend. her therapist points out that her thoughts, and not the situation itself, are the cause of her illness. this information suggests that leanne's therapist practices:

This information suggests that Leanne's therapist practices cognitive therapy.

Explanation:

"Cognitive therapy: A relatively short-term form of psychotherapy based on the concept that the way we think about things affects how we feel emotionally. Cognitive therapy focuses on present thinking, behavior, and communication rather than on past experiences and is oriented toward problem solving. Cognitive therapy has been applied to a broad range of problems including depression, anxiety, panic, fears, eating disorders, substance abuse, and personality problems."

Reference: Jr., William C. Shiel. “Definition of Cognitive Therapy.” MedicineNet, MedicineNet, 25 Jan. 2017

c. reserves power to the states and people