This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Water loss is severe if intestinal obstruction occurs at- 
Select and explain. 
A. First part of duodenum, B. Third part of duodenum, C. Midjejunum, D. Ileum
A: First part of duodenum
Answer: A: First part of duodenum 
Explanation: In high small bowel obstruction there is rapid vomiting and dehydration.