Which of the following separates the left and right sides of the rib cage?

The rib cage is a bony structure in the thorax that protects vital organs like the heart, lungs, and other major vessels while also serving as a framework for breathing. It is composed of the thoracic vertebrae, ribs, and sternum.

The sternum, also known as the breastbone, is a flat bone in the centre of the thorax. It connects to the rib bones on either side of the body, forming the front part of the rib cage. The sternum, by connecting to the ribs, helps to keep the rib cage in place and provides stability and protection to the heart, lungs, and other organs in the chest. The sternum thus separates the left and right sides of the rib cage, forming the front of the thorax and contributing to the overall structure of the thoracic cage.