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. - and whether, presuming such life forms having left fossil traces to begin with, those traces can
- and whether, if it is presumed that such life forms left some fossil traces to begin with, can those traces
- and whether, presuming such life forms left fossil traces to begin with, those traces
- and, presuming such life forms did leave some fossil traces to begin with, if they can
- and, presuming such life forms to have left fossil traces to begin with, if they
答案给的是A，不过我选C。
我们把presuming这里作为一个插入语，但是presuming后面应该跟一个有谓语的从句，这样并没有造成整个句子的run-on sentences
至于后面的those traces要不要can，我觉得关系不是特别大。
想听听大家的看法。谢谢 | 
