This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oesophagus, Subject name: Surgery
[{'content': 'Most common type of hiatus hernia: \nSelect and explain. \nA. Sliding, B. Rolling, C. Mixed, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) SlidingRef: Bailey and Love 27h Edition, Page 1083Sliding hiatus hernia in which OG junction enters the mediastinum via the wide hiatus,* Type 1: Sliding (Most common--70%)* Type 2: Paraesophageal/Rolling hernia* Type 3: Mixed* Type 4: Along with stomach, other structures like colon, spleen, pancreas or small bowel migrate into mediastinum.', 'role': 'assistant'}]