Scott uses exercise to gain a sense of control and accomplishment. He continues to exercise even though he has extreme tendinitis in his knees. Scott most likely has what disorder?

Activity Disorder

Explanation:

 According to the given question, Scott is suffering from the activity disorder due to the continuously doing exercise even he has tendinitis in his knees as he wants to gain sense of accomplishment and the control.

 In this type of disorder the person finds difficulty to control and manage their behavior in the stimuli and due to this they try to accomplished the high motor activity.

When the person is suffering from the extreme tendinitis in the knees he person should limit their activities for reducing  the stress, apply some ice for relief and also use the knee support. Therefore, Activity Disorder is the correct answer.