The patient's presentation of sudden-onset severe right lower quadrant pain, nausea, and rebound tenderness is classic for acute appendicitis. Rebound tenderness indicates peritoneal irritation, a key surgical sign necessitating prompt diagnosis and often emergent appendectomy to prevent complications such as perforation and abscess formation. While other options can cause abdominal pain, appendicitis typically localizes to the right lower quadrant and includes systemic signs like nausea and tenderness on physical exam. Early surgical intervention is critical to reduce morbidity.
Reference: Sabiston Textbook of Surgery, Townsend, 21st Edition.