Final answer:
b) Middle mediastinum
The heart and pericardium are located in the middle mediastinum of the thoracic cavity.
Step-by-step explanation:
The heart and pericardium are located within the thoracic cavity, specifically in the part of the mediastinum known as the middle mediastinum. The mediastinum is divided into different areas, with the middle mediastinum being the central compartment housing the heart, pericardium, roots of the great vessels, and various nerves. The pericardial cavity within the mediastinum is enveloped by the tough pericardium membrane, separating the heart from other mediastinal structures. This anatomical position is crucial for understanding not only the physical examination of the heart via stethoscope but also the interpretation of various medical imaging techniques.