Describe the anatomical position of the upper extremity.

The anatomical position is a standardized way of describing the orientation of the human body, especially important in the fields of medicine and anatomy. In this position, the individual stands upright with their feet together, and the arms are placed at the sides of the body with the palms facing forward. This orientation allows for a clear and consistent reference point for describing locations and movements of body parts.

Choosing the option that states "standing with arms at the sides" accurately reflects this definition of the anatomical position. It emphasizes the correct stance and arm placement, which is critical for understanding directional terminology in anatomy, such as anterior (front), posterior (back), medial (toward the midline), and lateral (away from the midline).

Other options describe different postures that do not conform to the established anatomical position. For example, sitting with arms crossed or legs extended changes the orientation of the body and does not provide the same clarity for anatomical reference. Similarly, standing with arms raised moves the arms away from the sides and affects the visualization of the body's structure and the relationships between various parts of the body.