请教og10th 155 locate reticent suspicious是如何并列的啊？

winnielxx

155.   Federal authorities involved in the investigation have found the local witnesses are difficult to locate, reticent. and are suspicious of strangers.
(A) the local witnesses are difficult to locate, reticent, and are
(B) local witnesses to be difficult to locate, reticent, and are
(C) that local witnesses are difficult to locate, reticent, and
(D) local witnesses are difficult to locate and reticent, and they are
(E) that local witnesses are difficult to locate and reticent, and they are
答案是c我选的e，我觉得c省略的太多了啊，suspicious前面的are 为什么可以省略呢？请高手指教。

winnielxx

明白了，谢谢