Final answer:
Psychologists would most likely use biofeedback to help clients reduce tension headaches.
Step-by-step explanation:
Biofeedback is a technique that uses electronic equipment to provide feedback in the form of visual or auditory signals to measure and help individuals gain voluntary control over normally involuntary bodily processes. It has been successfully applied in individuals experiencing tension headaches, among other conditions. Therefore, psychologists would most likely use biofeedback to help clients reduce tension headaches (c).