Which organ is located in the thoracic cavity and is responsible for respiration?

The lungs are the organs located in the thoracic cavity that are primarily responsible for respiration. They play a vital role in the respiratory system by facilitating the exchange of oxygen and carbon dioxide between the body and the environment. During inhalation, the lungs expand as air is drawn in, and during exhalation, they contract to expel carbon dioxide. This process is essential for maintaining adequate oxygen supply for cellular metabolism and removing waste gases from the bloodstream.

In the context of the other choices, the heart, while located in the thoracic cavity and critical for pumping blood, is not involved in the respiration process directly. The stomach and liver are located in the abdominal cavity and have functions related to digestion and metabolism, rather than respiration. Therefore, the lungs are the only correct answer with respect to the function of respiration within the thoracic cavity.