Mars

[crackgmat007]

It is theoretically possible that bacteria developed on Mars early in its history and that some were carried to Earth by a meteorite. However, strains of bacteria from different planets would probably have substantial differences in protein structure that would persist over time, and no two bacterial strains on Earth are different enough to have arisen on different planets. So, even if bacteria did arrive on Earth from Mars, they must have died out.
The argument is most vulnerable to which of the following criticisms?
A. It fails to establish whether bacteria actually developed on Mars.
B. It fails to establish how likely it is that Martian bacteria were transported to Earth.
C. It fails to consider whether there were means other than meteorites by which Martian bacteria could have been carried to Earth.
D. It fails to consider whether all bacteria now on Earth could have arisen from transported Martian bacteria.
E. It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out.

OA - D

[cramya]

Whats the argument saying?

No 2 strands of bacteria on Earth are any different and if some of them had come up from a different planet then the strand would be different. It assuming that some bacteria did originate on Earth or make us think of a remote possibility that it could have come from somewhere other than Mars if it dint orignate on Earth

YES AGREED but what if all bacteria now on earth are Martian bacteria (they are going to have the same strands since they came from only one planet i.e Mars) "So, even if bacteria did arrive on Earth from Mars, they must have died out" cannot be said by comparing the differences or similarity among the various strands.

D says the same thing as whats been said above.

[khanshainur]

I am pretty sure that the right Answer is D