小儿呼吸衰竭的诊断标准是

A.PaO≤8kPa(60mmHg),PaCO≥6kPa(45mmHg),SaO<90%

B.PaO≤8kPa(60mmHg),PaCO≥6.7kPa(50mmHg),SaO<90%

C.PaO≤6.7kPa(50mmHg),PaCO≥6.7kPa(50mmHg),SaO<85%

D.PaO≤6.7kPa(50mmHg),PaCO≥8kPa(60mmHg),SaO<85%

E.PaO≤6.7kPa(50mmHg),PaCO≥6.7kPa(50mmHg),SaO<90%