Which joints in the forearm are responsible for the supination and pronation actions?

The action of supination and pronation of the forearm is primarily facilitated by the proximal and distal radioulnar joints. The proximal radioulnar joint, located near the elbow, allows the head of the radius to pivot around the ulna when the palm is turned up (supination) or down (pronation). The distal radioulnar joint, located near the wrist, complements this motion as it enables the radius to rotate over the ulna, solidifying the rotation necessary for these actions.

By working in conjunction, these two joints facilitate the full range of motion needed for fine motor skills and many daily activities, such as turning a doorknob or using utensils. The other options do not accurately represent the joints involved in these specific movements; hence, they do not support the actions of supination and pronation effectively.