Final answer:
The heart is not found in the dorsal cavity; this cavity contains the central nervous system components such as the cerebellum, brainstem, and spine. The heart is located in the thoracic cavity.
Step-by-step explanation:
The dorsal cavity of the body does not contain the heart. This cavity mainly consists of the central nervous system components including the cerebellum, brainstem, and spine (spinal cord). The heart is actually located in the thoracic cavity, which is part of the ventral cavity, not the dorsal.
In contrast, the cerebellum aids in coordinating movement and learning new motor tasks, while the brainstem is involved in controlling a variety of autonomic functions and connects the brain with the spinal cord. The spinal cord, meanwhile, carries neural signals between the brain and the rest of the body. Therefore, the correct answer is B. heart, as it does not reside in the dorsal cavity.