Which two bones form the ball and socket joint of the upper arm?

The ball and socket joint of the upper arm is formed by the humerus and the scapula. This type of joint allows for a wide range of motion in multiple directions, enabling activities such as raising the arm, rotating, and swinging. The rounded end of the humerus (the ball) fits into the shallow depression of the scapula (the socket), providing the stability and flexibility needed for movement.

In contrast, the other options do not pertain to the correct anatomical structure in this context. The radius and ulna form the forearm's structure and are involved in elbow and wrist joints, while the clavicle and scapula are related in a different capacity, forming the shoulder girdle but not the ball and socket joint itself. The femur and pelvis are also unrelated as they involve the hip joint, not the shoulder area. This understanding clarifies the specific roles of these bones in the skeletal system and their relevance to joint movement.