请教一道语法题 （大全section4 23）

flyingsnail7

A huge flying reptile that died out with the dinosaurs some 65 million years ago, the Quetzalcoatlus had a wingspan of 36 feet, believed to be the largest flying creature the world has ever seen.
(A) believed to be
(B) and that is believed to be
(C) and it is believed to have been
(D) which was, it is believed,
(E) which is believed to be

答案选C，其他的选项确实有各自的错误，但是关于C我的疑问是：既然had和is believed的主语都是the Quetzalcoatlus， 两个谓语动词并列的时候为什么还要重复主语it呢？感觉不符合语法规则（就好像我们说， Amy came in and she sang a song. 这个句子里面的she显然是多于的吧~）   希望各位能帮忙解答！（最好能举一两个类似用法的OG、prep或是大全上的例子）先谢过了！！~

flyingsnail7

啊 隔了几天了都木有回复><先自己顶下。。。继续等解答~