What does the movement of supination involve in relation to the forearm?

Supination refers to the outward rotation of the forearm, which results in the palm facing upwards or forwards. When you think of the movement of supination, picture the action of holding a bowl of soup—your palm is oriented upward to keep the contents from spilling. This lateral rotation of the forearm involves the radius and ulna bones positioning parallel to each other, which is opposite to pronation, where the palm is facing downwards.

This definition and understanding of supination clearly align with the first choice, which describes the correct movement in detail. The other options relate to different bodily movements not associated with the forearm. Bending the foot in the direction of the sole or the shin pertains to ankle movements, while soles facing away from each other describes a stance related to the feet, thus being unrelated to the action of supination in the forearm.