Final answer:
A rupture of the celiac trunk would most directly affect the liver, stomach, and duodenum by disrupting their blood supply, potentially leading to ischemia and tissue damage.
Step-by-step explanation:
If Isabella's celiac trunk is ruptured as a result of an automobile accident, the organs most directly affected would be the liver, stomach, and duodenum. These organs receive their primary blood supply from the celiac trunk, an essential artery branching from the abdominal aorta. A rupture can lead to a significant disruption in blood flow, causing ischemia or lack of oxygen and nutrients, which can quickly lead to tissue damage or necrosis in these areas.