Q. A 16-year-old boy is brought to the clinic by his mother due to abdominal pain that started yesterday. Initially diffuse, the pain has now localized to the right lower quadrant. He also reports a low-grade fever and decreased appetite but does not have nausea, vomiting, or changes in bowel habits. His vitals are normal, except for a temperature recorded at 37.8°C (100°F). You suspect acute appendicitis. During the physical examination, which of the following signs is most commonly observed in cases of acute appendicitis?