The clavicle is a long, S-shaped bone that connects the sternum (breastbone) to the shoulder blade (scapula), hence its nickname "collarbone".
Key points about the other options: A. Scapula: This is the shoulder blade, not the collarbone. C. Sternum: This is the breastbone, where the clavicle attaches on one side. D. Humerus: This is the upper arm bone.