While most early robot designers equipped their robots

[saxenankit]

While most early robot designers equipped their robots with "legs," more recent robot designers have opted for movable treads,
which make continual contact with the ground over a wide area in contrast with specific spots on the ground.
A. in contrast with
B. rather than at
C. as opposed to at
D. instead of
E. as against

OE: B
Source: McGrawHill
Can any one of the experts please explain the logic that's used to get to the answer.

[tim]

after you do some of the work yourself. what did you notice about the sentence? what answers were you able to eliminate?

[saxenankit]

after you do some of the work yourself. what did you notice about the sentence? what answers were you able to eliminate?

I can narrow down to A or B .

[sanath.kumar.patro]

in contrast with- is wrong
rather than at- let us hold onto it
as opposed to at- it would have been right had it been were-as opposed to

instead of- a suspect in GMAT



as against- it is used to distinguish between two things but here we are comparing the same earth

So i will go with B as my answer.

Anyways, the instructors can throw some light at this problem......

[saravpreet.mib2011]

Just a humble attempt :-
It should basically be- the movable treads make contact with ground '- preposition + X rather than - preposition + Y'
i.e. the comparison shoul be between the two parts within single quotes. I think in this case, 'rather than' is an ideal comparitive tool as opposed to- in contrast with, as opposed to, instead of and as against.
option a) seems the comparison is between movable treads and specific spots on ground.
option b) correct
option c) awkward
option d) preposition missing with the second part (after instead of), which again makes it appear to be a comparison between movable treads and spots on ground.
option e) same reasoning as above.

[RonPurewal]

While most early robot designers equipped their robots with "legs," more recent robot designers have opted for movable treads,
which make continual contact with the ground over a wide area in contrast with specific spots on the ground.
A. in contrast with
B. rather than at
C. as opposed to at
D. instead of
E. as against

OE: B
Source: McGrawHill
Can any one of the experts please explain the logic that's used to get to the answer.

ughh, this question sucks. don't bother.

all of the answer choices (whether correct or incorrect) are trying to draw a parallelism/comparison/contrast between just "at specific spots on the ground" and "over a wide area" (i.e., two prepositional phrases).
the problem is that we need a larger parallel structure, because we also need something to be in contrast with "continual contact" -- i.e., the REAL contrast here is
continual contact with the ground over a wide area
vs.
discrete/isolated/separate contact at specific spots on the ground

unless the contrast is drawn between these entire phrases -- with the boldface words inserted -- the sentence is nonsense. so all 5 of the existing choices are very, very wrong.

this is currently the only problem i have seen from "mcgraw-hill", so i'm going to wait until i see others to make a final judgment; however, that source is now on my mental list of sources that may deserve to be banned.

[saxenankit]

While most early robot designers equipped their robots with "legs," more recent robot designers have opted for movable treads,
which make continual contact with the ground over a wide area in contrast with specific spots on the ground.
A. in contrast with
B. rather than at
C. as opposed to at
D. instead of
E. as against

OE: B
Source: McGrawHill
Can any one of the experts please explain the logic that's used to get to the answer.

ughh, this question sucks. don't bother.

all of the answer choices (whether correct or incorrect) are trying to draw a parallelism/comparison/contrast between just "at specific spots on the ground" and "over a wide area" (i.e., two prepositional phrases).
the problem is that we need a larger parallel structure, because we also need something to be in contrast with "continual contact" -- i.e., the REAL contrast here is
continual contact with the ground over a wide area
vs.
discrete/isolated/separate contact at specific spots on the ground

unless the contrast is drawn between these entire phrases -- with the boldface words inserted -- the sentence is nonsense. so all 5 of the existing choices are very, very wrong.

this is currently the only problem i have seen from "mcgraw-hill", so i'm going to wait until i see others to make a final judgment; however, that source is now on my mental list of sources that may deserve to be banned.

Dear Ron,

I understand your concern here. Is it possible that you share your mental list of sources that you think should be banned. You know, this sharing might help a lot of students like me. We could save our time and effort by not touching such sources.

Thanks in advance,
Ankit Saxena

[tim]

LOL listing bad sources is too much of a task; there are so many of them. :) Just stick with MGMAT problems and official materials (OG, GMAT Prep) and you'll have more than enough practice material and won't have to worry about questionable sources..