Previous Question Correct Answer Is (d) Peptic ulcers Peptic ulcers are most commonly caused by: *Helicobacter pylori (H. pylori) infection:* This bacterium weakens the protective mucus lining of the stomach and duodenum, allowing stomach acid to damage the underlying tissue. *Nonsteroidal anti-inflammatory drugs (NSAIDs):* Long-term use of NSAIDs, such as aspirin, ibuprofen, and naproxen, can irritate the stomach lining and increase the risk of ulcer development. While stress and diet may worsen ulcer symptoms, they are not typically considered direct causes. Genetic factors can play a role in susceptibility to H. pylori infection, but they don't directly cause ulcers.