44 As officers of the United States government are free to disagree with each other, _______are its citizens.
(A) they
(B) who
(C) and
(D) so

你只要聽過"種瓜得瓜，種豆得豆"這句英文諺語的話，這句話就很好解釋了：

As you sow, so shall you reap.
如你所播種的，你也會如此的收成：種瓜得瓜，種豆得豆

你的這題題目也是從這個句型脫胎而來的：

As S1 + V1, so + 助動詞 + S2 + V2
如S1一樣，S2也是如此

這裡的so就好像我們平常在說：So do I.  So am I. (我也是) 的用法是一樣的。

所以你的句子：

As officers of the United States government are free to disagree with each other, so are its citizens.
後半句的主詞是its citizens，動詞則是are了。
完整的寫法會是：

. . . . so are its citizens free to disagree with each other.

As officers of the United States government are free to disagree with each other, so are its citizens.由於美國政府官員可以自由地相互提出異議，其公民也是如此。