H pylori -

Ans. is 'b' i.e. Obligate parasite on gastric mucosa H. pylori, though initially infects the gastric mucosa only, may later on infect the duodenal mucosa. the process is as follows : Infection of gastric mucosa leads to hypergastrinemia and acid hypersecretion. Acid hypersecretion leads to metaplasia in the duodenal mucosa. "This duodenal metaplasia allows H. pylori to colonize the duodenal mucosa and in these patients, the risk of developing a duodenal ulcer increases 50 fold" - Schwaz