Final answer:
The Subscapularis is not targeted during the posterior shoulder ball roll, as it is located on the front (anterior) side of the scapula, unlike the infraspinatus, supraspinatus, and teres minor which are targeted.
Step-by-step explanation:
The muscle that is not targeted during the posterior shoulder ball roll is C) Subscapularis. The posterior shoulder ball roll mainly targets the muscles at the back of the scapula, which include the infraspinatus, supraspinatus, and teres minor. These muscles are part of the rotator cuff, which plays a crucial role in shoulder movements and stability. However, the subscapularis is located on the anterior side of the scapula, and it is involved in medially rotating the arm. Therefore, it is not directly targeted during exercises that focus on the posterior shoulder, like the ball roll.