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
Most Severe degree of alkalosis occurs in obstruction of - 
Select and explain. 
A. Cardiac end, B. Pylorus, C. Ileocaecal region, D. Colon
B: Pylorus
Answer: B: Pylorus 
Explanation: • Gastric alkalosis is most marked with vomiting due to pyloric stenosis or obstruction because the vomitus is acidic gastric juice only.
• Vomiting in other conditions may involve a mixture of acid gastric loss and alkaline duodenal contents and the acid-base situation that results is more variable.
• Loss of alkaline small intestinal contents can even result in an acidosis if gastric acid secretion is suppressed.