Which of the following conditions occurs when the intestine is obstructed?

The correct answer is intestinal obstruction because this condition specifically refers to a blockage of the intestines that prevents the normal passage of contents through the digestive tract. When an obstruction occurs, it can lead to a variety of complications including buildup of fluids and gases, reduced blood flow to the intestines, and potential damage to the intestinal wall.

In contrast, peritonitis is an inflammation of the peritoneum, often due to infection or perforation of the gastrointestinal tract but not exclusively caused by obstruction. Hernia refers to the protrusion of an organ through an abnormal opening, which can sometimes lead to obstruction, but is distinct from the obstruction itself. Mesenteric infarction is a condition resulting from blood supply loss to the intestines, which can occur as a complication of an obstruction but is not synonymous with obstruction. Each of these conditions is related in some way to intestinal health but represents different pathological scenarios.