Which of the following is NOT part of the ventral cavity?

The cranial cavity is indeed not part of the ventral cavity. The ventral cavity refers specifically to the larger body cavity in humans that is located toward the front of the body and is divided into the thoracic cavity and the abdominopelvic cavity (which includes both the abdominal and pelvic cavities).

The thoracic cavity contains organs such as the heart and lungs, while the abdominal cavity houses digestive organs like the stomach and intestines, and the pelvic cavity contains the bladder and reproductive organs. The cranial cavity, however, is part of the dorsal cavity, which houses the brain and is located toward the back of the body. Therefore, the correct identification of the cranial cavity as separate from the ventral cavity is what makes this choice accurate.