Final answer:
The liver is the organ that fits the description of being located beneath the diaphragm, protected by the rib cage, and held in place by ligamentous attachments.
Step-by-step explanation:
The organ located beneath and attached to the diaphragm, protected by the rib cage, and held in place by ligamentous attachments is the liver. The rib cage consists of the ribs, sternum, thoracic vertebrae, and costal cartilages. It encloses and protects important organs including the liver and lungs. The ribs are categorized into three groups: true ribs, false ribs, and floating ribs, which provide varying levels of structural support and flexibility for breathing movements. The liver, an accessory digestive organ, plays significant roles in metabolism and regulation and receives protection from the rib cage. Additionally, the diaphragm, a key muscle in the respiratory process, attaches to various structures including the xiphoid process of the sternum, the lower ribs and their cartilages, and the lumbar vertebrae.