请教一个关于动名词的选择题
If Mary doesn’t come to work on time,she may be fired.
--Surely she is not so foolish ___________ it.
A.as not to realize
B.not as to realize
C.that she didn’t realize
D.as not realizing
解析一下这题该怎么选,以及他三个选项错误的原因分别是什么.