A patient comes to the emergency room with pain in his stomach and a history of irregular bowel movements. Which problem is most likely causing these symptoms?

Stomach pain and irregular bowel movements point to a problem in the digestive system. Irritable bowel syndrome can cause abdominal pain and changes in bowel habits, so choice A best fits. Lactose intolerance is also digestive, not urinary, and kidney infections involve the urinary system rather than irregular bowel movements.

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