單項選擇題COPD患者肺功能回報:FEV1/FVC<56%,F(xiàn)EV1/預計值:45%,該患者按COPD嚴重程度分級屬于()

A.輕度COPD
B.中度COPD
C.重度COPD
D.極重度COPD
E.高危COPD