Which of the following cavities includes both the abdomen and pelvis?

The abdomino-pelvic cavity is the correct answer because it encompasses both the abdominal and pelvic regions of the body. This cavity is a single entity that houses various vital organs, including those belonging to the gastrointestinal, urinary, and reproductive systems.

Anatomically, the abdominal cavity is located superiorly and contains organs such as the stomach, liver, and intestines, while the pelvic cavity, found below the abdominal cavity, houses the bladder and reproductive organs. The term "abdomino-pelvic" is used to highlight that these two regions are connected and form a continuous space in the human body.

The other cavities mentioned are distinct and do not encompass both the abdomen and pelvis. The cranial cavity, for example, is enclosed by the skull and contains the brain. The thoracic cavity is located above the diaphragm and contains the heart and lungs. The spinal cavity surrounds the spinal cord within the vertebral column. Each of these cavities has separate functions and anatomical boundaries, distinguishing them from the combined space of the abdomino-pelvic cavity.