Which bones are primarily found in the arm?

The correct choice identifies the primary bones of the arm as the humerus, ulna, and radius. The humerus is the long bone in the upper arm that runs from the shoulder to the elbow. The ulna and radius are the two bones in the forearm. The ulna is located on the side opposite the thumb and is crucial for the movement and stability of the elbow joint. The radius is situated on the same side as the thumb and is important for wrist function. Together, these three bones allow for a range of motions in the arm, including flexion, extension, and rotation.

In contrast, the other options focus on different areas of the body or groups of bones. Metacarpals, carpals, and phalanges are found in the hand and fingers rather than in the arm itself. The scapula and clavicle connect the arm to the body and are not classified as arm bones. Finally, the femur, tibia, and fibula are bones located in the leg, not the arm. Each of these incorrect options highlights structures or groups not specifically related to the arm, making them unsuitable choices for this question.