A nurse is assessing a client who is two weeks postoperative following a live donor kidney transplant. Which assessment finding would the nurse identity as possible organ rejection?

A. Oliguria: A decrease in urine output is one of the earliest and most sensitive indicators of acute kidney transplant rejection. Immunologic injury to the graft leads to inflammation, vascular compromise, and reduced glomerular filtration rate, resulting in diminished urine production and rising serum creatinine levels. B. Anorexia: Loss of appetite can occur in many postoperative or chronic illness states and is not specific to transplant rejection. It does not directly reflect graft dysfunction or immunologic injury to the transplanted kidney. C. Confusion: Altered mental status may be associated with metabolic imbalances, medications (e.g., immunosuppressants), or uremia, but it is a late and nonspecific finding. It does not directly indicate early graft rejection. D. Pain: Some discomfort at the transplant site may be present postoperatively, but pain alone is not a reliable indicator of rejection. While graft tenderness can occur, it is less specific than changes in renal function such as decreased urine output.