This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Anatomy
[{'content': 'Obstruction of IVC leads to \nSelect and explain. \nA. Dilatation of thoracoepigastric veins, B. Caput medusae, C. Hemorrhoids, D. Esophageal varices', 'role': 'user'}, {'content': 'Answer: A \nExplanation: .', 'role': 'assistant'}]