Another of Hoyle's arguments can be summarized as follows:

Tough one.....

Is it A??

IMO C, but this one doesn't seem like GMAT style.

Will go with C here.

D and E are out they incorrect refer weaken and strengthen respectively wheras D strengthens and E weakens.

A - Drawing analogy between other substances cannot help the argument.
B - Incorrect. It draws analogy between methane produced in Earth and methane produced on ET bodies.

C - the best choice. Obviously the argument doesnot produce any evidence other than drawing an analogy. It can be strenghten if the process of methanogens can be explained and compared with the condition on ET bodies.

Which of the following is true of this argument?

A) It would be strengthened by the discovery of other compounds which occur both on earth and in comets, and whose terrestrial occurrence is strongly correlated with bacterial action.

B) Since this argument appeals to no analogies between terrestrial and extra-terrestrial phenomena, it does not need any explanation of how methanogens synthesize methane. out of scope

C) This argument has no evidential force with respect to the extra-terrestrial existence of bacteria unless it can be supplemented with an explanation of the process by which terrestrial bacteria synthesize methane. no

D) The plausibility of Hoyle's conclusion would be seriously weakened if on-site explorations of other planets in our solar system were to reveal the existence of methanogenic bacteria there. would rather be strengthned

E) It would be strengthened if it were discovered that methane is generated in Antarctica, without bacterial action, at low temperatures, which approximate those of comets far out in the solar system. it seems the one links the two thesis

It is really a tough one for me. I will go with C.

A it is

C for me

C it should be ............

D & E are 180 to what is said in the argument.

A & B- Out of Scope (Other Things)

OA is A

OE:
(A) is the only alternative which fits the description given of Hoyle's argument The argument clearly does appeal to a similarity between terrestrial and extra-terrestrial phenomena --that methane occurs both on earth and in comets. It concludes that there (probably) is a further similarity-that the methane in comets is the product of bacteria, just as it invariably is on earth. This line of argument would, of course, be strengthened by the discovery of further similarities of the first kind; for example, other compounds which occur in both places, and whose terrestrial occurrence is, like that of methane, strongly linked to bacterial action.
(B) cannot be correct, since it denies that the original argument appeals to an analogy.
Concerning (C), the argument might be strengthened if we had some good account of the process of bacterial production of methane. But we might know that this production is a fact, and even that it is, so far as we can tell, the only source of terrestrialmethagens without knowing that process. And in that case the analogy would still have some evidential force with respect to what happens extraterrestrially.
The scenario in (D) would strengthen the plausibility of Hoyle's conclusion; indeed, it is hard to think of anything that would strengthen it more.
The events described in (E) would weaken it by revealing an analogy which suggests a non-organic source of methane in comets.

Has to be A.