新版sat og 430页第7题,语法.

新版sat og 430页第7题,语法.
我以为乃们都有OG的。
the shift from traditional to cosmetic dentistry 【is because adults are getting fewer cavities and becoming】more vain.
A.原句
B.is because of adults getting fewer cavities and their becoming
C.is caused from adults getting fewer cavities and in addition become
D.is occuring because adults are getting fewer cavities and becoming