来看一道GWD SC 到底什么时候宾语从句that引导词可以省略？

zlljolie

NASA’s methodical approach to the exploration of Mars has not yet answered the questions of whether biological life forms ever emerged on Mars and whether, presuming such life forms having left fossil traces to begin with, those traces can still exist in some moist recesses of the cold and arid planet.



A.and whether, presuming such life forms having left fossil traces to begin with, those traces can

B.and whether, if it is presumed that such life forms left some fossil traces to begin with, can those traces

C.and whether, presuming such life forms left fossil traces to begin with, those traces

D.and, presuming such life forms did leave some fossil traces to begin with, if they can

E.and, presuming such life forms to have left fossil traces to begin with, if they
这题正确答案选择C。
以前也做过这种类似的题目，presume(that)这种that省略了，GMAC语法 宾语从句引导词that不是不可以省略的吗？
请大牛解释的啊。。。
不过从语意上，C是最好的。但是这里的that省略纠结了。。。

lpbird

以前看到过可以省的，不是绝对不能省