Which cavity contains the urinary bladder and reproductive organs?

The pelvic cavity is the correct choice because it is specifically designated for the housing of structures like the urinary bladder and reproductive organs. This cavity is located below the abdominal cavity and is surrounded by the bones of the pelvis. Within the pelvic cavity, the urinary bladder is situated anteriorly, while the reproductive organs—such as the ovaries, uterus, and prostate—are located in positions specific to their anatomical functions.

In contrast, the thoracic cavity contains the heart and lungs, while the abdominal cavity houses organs like the stomach, liver, and intestines. The spinal cavity, also known as the vertebral cavity, encases the spinal cord. None of these alternatives provide the necessary support and protection for the urinary bladder and reproductive structures like the pelvic cavity does. Therefore, the pelvic cavity is uniquely suited for the contents it holds, making it the correct answer.