A.I. Explanation:

Option 1: "Pain killers."

Explanation: The text mentions that pain killers are a traditional response to back pain, but it does not indicate that the clinic mainly recommends them. Instead, it emphasizes the unique benefits of relaxation therapy.

Option 2: "Relaxation therapy."

Explanation: The text highlights that the clinic is beginning to realize the unique benefits of relaxation therapy as a treatment for back pain. This aligns with the main idea of the text, which suggests a shift in focus from traditional methods to relaxation therapy.

Option 3: "Mind altering drugs."

Explanation: The text does not mention mind-altering drugs at all. This option is not supported by any information in the text and is therefore irrelevant.

Option 4: "Exercise routines."

Explanation: While the text acknowledges that some specialists advocate for certain types of exercise, it also states that these can be mishandled and lead to more harm than good. Thus, the clinic does not primarily recommend exercise routines.