809. The proposed urban development zones do not represent a new principle; it was employed in “Operation Bootstrap” in Puerto Rico.
(A) do not represent a new principle; it
(B) represent not a new principle, but one that
(C) are not a new principle; the same one
(D) are not a new principle, but one that
(E) are not new in principle; it

看了之前的帖子还是不太懂one的意思

以前的帖子说
one是指单数名词短语的核心词

请问核心词是什么啊?在这题里又是指什么呢?

谢谢

核心词就是去掉诸多修饰成分最后留下的名词

本题指代principle