自动充气式气囊不连接氧源，氧浓度为（）。

A.85%
B.90%
C.95%
D.100%

A.0.80~0.85
B.0.85~0.90
C.0.90~0.92
D.0.92~0.95

A.21%~40%
B.21%~50%
C.30%~40%
D.21%~60%