BenjaminWS wrote:
I choose D with the below explanation.
The conclusion is "some of the planets in oval orbits around distant stars were probably thrown into those orbits by close encounters with other planets orbiting the same stars."
To strengthen the conclusion, D says that
"(D) Most comets with an oval orbit around our sun were thrown into that orbit by a close encounter with some other object."
,so these comets were thrown into that orbit by a close encounter.
This is the same reasoning as the conclusion.
GMATNinja , Could you please help us?
According to the passage, because many
comets have oval orbits as the result of close encounters with planets orbiting the sun, some
planets have oval orbits as a result of close encounters with other planets. But how do we know that these planets are comparable to comets? The author seems to assume that the orbits of planets and comets are similar, but he/she provides no basis for doing so.
The question asks for an answer choice that would strengthen the argument. With that in mind, here’s (D):
Quote:
(D) Most comets with an oval orbit around our sun were thrown into that orbit by a close encounter with some other object.
The passage has already established that MANY comets orbiting the sun are thrown into oval orbits by close encounters with planets. (C) only adds that MOST comets with oval orbits were thrown into oval orbits by a close encounter with some other object.
But we still have no reason to believe that comets and planets are similar. And while we have more information about
comets, we don’t have any additional information about
planets. For that reason, we can eliminate (D).
I hope that helps!