Another question

[dongkim2]

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 wether, if it is presumed that such life forms some fossil traces to begin with, can those traces
c. and whther, presuming such life left fossil traces to begin with, can thoses 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

Please let me know what the answer is. Thanks!

[kanha81]

It is quite hard to follow through this sentence.

[amitabhprasad]

From the choice given I will go with "A".
I just used parallelism on either side of "and"
Though I am not comfortable with any of the choices.

[kanha81]

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 wether, if it is presumed that such life forms some fossil traces to begin with, can those traces
c. and whther, presuming such life left fossil traces to begin with, can thoses 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

Please let me know what the answer is. Thanks!

Here's my reasoning:
[spoiler]a. and whether, presuming such life forms having left fossil traces to begin with, those traces can[/spoiler]
Keeps the meaning intact.

b. and wether, if it is presumed that such life forms some fossil traces to begin with, can those traces

Awkward

c. and whther, presuming such life left fossil traces to begin with, can thoses traces

changes the meaning - it is life forms and not just life

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

I am confused as who is "they" referring

e. and, presuming such life forms to have left fossil traces to begin with, if they

I like this answer better but I have same confusion as [D]

What is OA? Would like to know.

[Bidisha800]

(A) -

source ?