School integration plans that involve busing between suburban and central-city areas have contributed, according to a recent study, to significant increases in housing integration, which, in turn, reduces any future need for busing.
(A) significant increases in housing integration, which, in turn, reduces (B) significant integration increases in housing, which, in turn, reduces (C) increase housing integration significantly, which, in turn, reduces (D) increase housing integration significantly, in turn reducing (E) significantly increase housing integration, which, in turn, reduce
请教各位大侠, 选(a)是因为主词是 housing integration吗? 我不懂的是主词为什么不是increases in housing integration呢? 这样句意看来似乎也是通顺的。