What does the thoracic cavity primarily include?

The thoracic cavity primarily includes the heart and lungs, making that the correct choice. This cavity is an essential part of the human body that houses vital organs involved in respiratory and circulatory functions. The heart is responsible for pumping blood throughout the body, while the lungs are critical for gas exchange, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled.

The other options reference organs that do not belong to the thoracic cavity. The brain is housed within the cranial cavity, while the stomach and pancreas are situated in the abdominal cavity. Thus, the inclusion of the heart and lungs in the thoracic cavity accurately reflects the anatomical structures found within that region.