Final answer:
The radius bone is located on the thumb side (lateral side) of the forearm, where it articulates with the humerus and carpal bones and supports the interosseous membrane attachment.
Step-by-step explanation:
The radius bone is situated on the side of the forearm that corresponds to the thumb, which is known as the lateral side of the forearm. When specifically addressing the question about its location related to the pinky or thumb side, the radius is found on the thumb side (B). It runs parallel to the ulna, which is located on the medial side of the forearm. The radius articulates with the capitulum of the humerus at the elbow joint and with carpal bones at the wrist joint. This placement facilitates articulation with the humerus at the elbow and with two carpal bones to form the wrist joint, while also allowing the interosseous membrane to attach to the interosseous border of the radius, which runs parallel to the ulna.