In those years, a very young mother was not as common as it is now.

A)
那些年,年轻的妈妈比现在普遍。

B)
那些年,年轻的妈妈不如现在普遍。

C)
那些年,年轻的妈妈跟现在一样普遍。
出自:大学英语(1)