What symptom does irritable bowel syndrome typically exhibit?

Irritable bowel syndrome (IBS) is characterized by a range of gastrointestinal symptoms, primarily focusing on the function of the intestines rather than any structural abnormalities. One of the hallmark symptoms of IBS is bloating and gas, which occur due to abnormal intestinal motility and increased sensitivity in the gastrointestinal tract. Patients with IBS often report discomfort or distention in the abdomen, accompanied by symptoms like cramping, diarrhea, or constipation.

The other options mentioned are not typical symptoms of IBS. Dark urine generally indicates dehydration or other systemic issues, weight loss can occur due to various other medical conditions but is not a primary symptom of IBS, and abdominal scarring is associated with diseases that cause inflammation or structural changes in the intestines, such as Crohn's disease, rather than IBS. Therefore, bloating and gas are the symptoms that most effectively encapsulate what someone with IBS might experience.