Which position is defined by standing straight with arms at the sides and palms facing forward?

The position described as standing straight with arms at the sides and palms facing forward is known as the anatomical position. This is a standard reference point used in anatomy to ensure clarity in communication when describing locations and movements of the body. In the anatomical position, the body is upright with a standard orientation that allows for consistent terminology among healthcare professionals.

This position is critical for understanding anatomical direction terms, such as superior (above) and inferior (below), as it provides a uniform frame of reference regardless of how the body is actually positioned during examination or discussion. The other options do not fit this definition: "prone" refers to lying face down, "sitting" is a position where the body is upright but not fully standing, and "supine" is lying flat on the back.