**Core Concept:**
The question pertains to the anatomy and function of the muscles involved in shoulder movements, specifically shoulder abduction. In the human body, shoulder abduction is a movement where the arm is lifted away from the body, moving it upward and outward from the body. In this case, we are focusing on the range of motion (15 to 90 degrees).

**Why the Correct Answer is Right:**
The correct answer, **D**. Serratus Anterior, is the muscle responsible for shoulder abduction in the scapular plane. The serratus anterior muscle is a flat, fan-shaped muscle located on the lateral (outside) wall of the chest, attaching from the seventh cervical vertebrae to the inferior angle of the scapula (shoulder blade). When this muscle contracts, it pulls the scapula upward and laterally, causing shoulder abduction in the plane where the arm moves upward and away from the body while staying close to the chest wall.

**Why Each Wrong Option is Incorrect:**
A. **Correct Answer:** None of the options A (Triceps Brachii), B (Subscapularis), or C (Rhomboideus Musculus) are involved in shoulder abduction within the scapular plane. The triceps brachii is a muscle of elbow flexion and extension, subscapularis is responsible for internal rotation and rotation, and rhomboideus musculus is involved in scapular depression and rotation.

B. **Correct Answer:** None of the options A (Supraspinatus), B (Subscapularis), or C (Rhomboideus Musculus) are involved in shoulder abduction within the scapular plane. The supraspinatus is responsible for external rotation and rotation, subscapularis is involved in internal rotation and rotation, and rhomboideus musculus is associated with scapular depression and rotation.

D. **Correct Answer:** The correct answer, **D**. Serratus Anterior, is responsible for shoulder abduction in the scapular plane. As mentioned earlier, this muscle attaches from the seventh cervical vertebrae to the inferior angle of the scapula, and when activated, it pulls the scapula upward and laterally, causing shoulder abduction in the plane where the arm moves upward and away from the body while staying close to the chest wall.

E. **Correct Answer:** None of the options A (Triceps Brachii), B (Subscapularis), C (Rhomboideus Musculus), or D (Serratus Anterior) are involved in this specific movement. The triceps brachii is a muscle of elbow flexion and extension, subscapularis is responsible for internal rotation and rotation, rhomboideus musculus is associated with scapular depression and rotation, and serratus anterior is the muscle responsible for shoulder abduction in the scapular plane.

**Core Concept:** Understanding the anatomy and function of different muscles in the shoulder girdle is essential for understanding various movements and their corresponding muscles. In the context of this question, we are focusing on