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: Medicine
Commonest site of peptic ulcer is : 
Select and explain. 
A. 1st pa of Duodenum, B. IInd pa of duodenum, C. Distal 1/3 of stomach, D. Pylorus of the stomach
A: 1st pa of Duodenum
Answer: A: 1st pa of Duodenum 
Explanation: Answer is A (1st pa of Duodenum) First pa of duodenum is the most common site for peptic ulceration. Sites in order of decreasing frequency : Duodenum, 1st poionQ Stomach, usually antrum Q At the gastro-esophageal junction, in the setting of gastroesophageal reflux Q Within the margins of a gastrojejunostomy Q In the duodenum, stomoch or jejunum of patients with Zollinger- Ellison Syndrome Q Within or adjacent to a Meckels diveiculum that contains ectopic gastric mucosa Q Peptic ulcers are usually solitary lesions less than 4 cm in diameter