48.下肢血氧高於上肢的現象，較常見於下列何種先天性心臟病？ (A) 大動脈轉位合併開放性動脈導管 ( transposition of great artery with patent ductusarteriosus )(B) 心室中膈缺損 ( ventricular septal defect )(C) 法洛氏四重症 ( tetralogy of Fallot )(D) 肺靜脈回流異常 ( total anomaly of pulmonary venous return )