Which of the following is contained in the thoracic cavity?

The thoracic cavity is a vital area of the body that houses key organs involved in vital functions. One of the primary organs contained within this cavity is the heart, which is situated within the mediastinum, a central compartment. This cavity is encased by the rib cage, providing a protective structure for the heart and the lungs, which are also located in the thoracic cavity.

In contrast, the bladder, kidneys, and liver are all located in other body cavities. The bladder is found in the pelvic cavity, while the kidneys are located in the retroperitoneal space, which is behind the peritoneum, a membrane that lines the abdominal cavity. The liver resides in the upper right part of the abdominal cavity. This anatomical distinction underscores why the heart is the correct answer, as it is specifically an organ found within the thoracic cavity, playing a crucial role in the circulatory system.