Final answer:
Esophageal varices are most likely caused by portal hypertension, which is the increased blood pressure in the portal vein system due to liver disease. These varices can rupture and cause life-threatening bleeding.
Step-by-step explanation:
Esophageal varices are most likely caused by portal hypertension, which is the increased blood pressure in the portal vein system due to liver disease. When blood flow is obstructed in the liver, the blood backs up and seeks alternative routes to return to the heart. This leads to the development of new blood vessels, including esophageal varices, which are enlarged and swollen veins in the lower part of the esophagus. These varices can rupture and cause life-threatening bleeding.