Critical Reasoning

For years, scientists have proposed the idea that Mars was once covered by two huge oceans. However, ridges of rock in the northern hemisphere that seem to resemble a shoreline are too hilly to be the edges of an ocean. If it could be shown that something caused an imbalanced portion of the planet's mass to shift from these ridges of rock toward the equator, where the mass now lies, it is possible that the ridges were once actually smooth.

Which of the following can be inferred from the statements above?

a)If it is determined that the ridges of rock in the northern hemisphere of Mars were never smoother than they now are, oceans did not exist on the planet.
b) The discovery that some of Mars' equatorial mass was once part of northern-hemisphere rock ridges would support the idea that the planet was once covered by oceans.
c) If the rock ridges in the northern hemisphere of Mars were smooth at one time, some the planet's mass was once closer to the equator
d) In order for a planet to have oceans, a portion of the planet's mass must have been shifted towards the equator.
e) There is general agreement in the scientific community that Mars does not have the right atmospheric conditions to support an ocean.

My answer a as it talks about ridges being smoother or not as that is the measure of presence of ocean..

src_saurav wrote:For years, scientists have proposed the idea that Mars was once covered by two huge oceans. However, ridges of rock in the northern hemisphere that seem to resemble a shoreline are too hilly to be the edges of an ocean. If it could be shown that something caused an imbalanced portion of the planet's mass to shift from these ridges of rock toward the equator, where the mass now lies, it is possible that the ridges were once actually smooth.

Which of the following can be inferred from the statements above?

a)If it is determined that the ridges of rock in the northern hemisphere of Mars were never smoother than they now are, oceans did not exist on the planet.

This answer choice is tempting, but what it says cannot actually be inferred from what is said in the passage. The passage merely says that particular ridges are too hilly to be part of a shoreline. It does not say that therefore oceans never existed on the planet.

b) The discovery that some of Mars' equatorial mass was once part of northern-hemisphere rock ridges would support the idea that the planet was once covered by oceans.

This can be inferred from the passage. If some of Mar's equatorial mass were once part of those ridges that situation would indicate that the ridges may have once been smoother, and that in turn would indicate that the ridges could once have been the edges of an ocean. That possibility supports the idea that the planet was once covered by oceans.

c) If the rock ridges in the northern hemisphere of Mars were smooth at one time, some the planet's mass was once closer to the equator.

This does not make sense as the passage talks of the ridges becoming less smooth via mass shifting toward the equator. So if they were smooth at one point, the mass would at that point have been further from the equator, not closer.

d) In order for a planet to have oceans, a portion of the planet's mass must have been shifted towards the equator.

This cannot be inferred. This answer choice incorporates a clear logical flaw that involves taking an atypical case and generalizing from it.

e) There is general agreement in the scientific community that Mars does not have the right atmospheric conditions to support an ocean.

This answer choice can easily be eliminated as atmospheric conditions are not discussed and the passage does not include any information that can be used to infer what scientists believe about atmospheric conditions.

So the correct answer is b.

I agree with Murrah.
The contention is that ocean edges are not "hilly" as seen on the ridges in the northern hemisphere.
These ridges are likely to be the mass deposited at the equator.

If it can be proved that the said mass at the equator are actually part of the ridges in the North,
we can reasonably assume the space was a pre-exisiting ocean.

I think that needed inference is provided in B.

a)'oceans did not exist on the planet' this is the opposite of what the author wants to say although it maybe a lucrative answer choice
c)In this option there is no description of the fact 'that ocean existed once on the planet' which is a part of the main conclusion.
d)'a portion of the planet's mass 'must' have been shifted' this an exaggeration of the line by using 'must' which is not permissible for main point questions.
e)It is simply an out of scope answer.

Correct choice therefore is b) my friend...yolo