A 42-year-old male presents to the clinic with complaints of burning epigastric pain that has been intermittent for the past two months. He describes the pain as gnawing and localized to the upper abdomen. The pain typically occurs 3 to 4 hours after eating and frequently wakes him up at night. He notes that the discomfort is relieved by eating a small meal or taking over-the-counter antacids, though the relief is temporary. He denies significant weight loss, fever, or changes in bowel habits. However, he reports occasional bloating and nausea. The patient works as an office manager and admits to high stress levels. He takes ibuprofen frequently for chronic knee pain and drinks three to four cups of coffee daily. He smokes about 10 cigarettes per day but denies alcohol consumption. There is no personal or family history of gastrointestinal conditions. On physical examination, the patient appears well but slightly uncomfortable. Vital signs are within normal limits. Abdominal examination reveals mild tenderness in the epigastrium without guarding or rebound tenderness. No palpable masses are noted, and bowel sounds are normal. Rectal examination shows no evidence of melena or occult blood. Which of the following is the most common cause of this type of ulcers?
