单项选择题

A.上颌21缺失,11,22为基牙
B.上颌11,21缺失,12,22为基牙
C.上颌26缺失,25,27为基牙
D.下颌34,35缺失,33,36为基牙
E.下颌34缺失,33,35为基牙