Final answer:
The abdominal cavity is the space within the abdomen that houses various organs such as the digestive organs and kidneys, while the peritoneal cavity is a fluid-filled subset of the abdominal cavity that is lined by the peritoneum, providing lubrication to the organs.
Step-by-step explanation:
The difference between the abdominal and peritoneal cavities lies in their anatomical definitions and spatial relations within the body. Option A states that the abdominal cavity is the space within the abdomen, which includes the region that houses the digestive organs and the kidneys, and the peritoneal cavity is a subset of this abdominal cavity. The peritoneal cavity, bounded by the visceral and parietal peritoneum, is the fluid-filled space within the abdominal cavity that provides lubrication to the organs. This option correctly describes the relationship between the two cavities.