Which of the following organs is NOT typically found in the abdominal cavity?

The rectum is the correct answer because it is located in the pelvic cavity rather than the abdominal cavity. The abdominal cavity contains many vital organs involved in digestion and metabolism, such as the liver, spleen, and intestines. The liver processes nutrients from the digestive system, the spleen is involved in blood filtration and immune function, and the intestines are essential for nutrient absorption and waste elimination.

In contrast, the rectum serves as a part of the lower gastrointestinal tract, specifically located in the pelvis where it is involved in the storage and expulsion of feces. This anatomical distinction is crucial for understanding the organization of the body's cavities and how various organs are grouped based on their functions and locations.