Unlike regulators in Europe who aim to prevent airlines from building

please help me understand this problem

Why not A? Confused between A and B

Correct answer is B

Use of although presents contrast, but it does not present the sense of comparison between two entities.

Use of although conveys that the regulators in America should also aim to prevent monopoly given that the European regulators are doing that.

Can someone explain what is wrong with adding who on C? Thanks

generis ,

Could you please explain b vs D ?

Regards,
Arup

baliga007 , mykrasovski (sorry, missed your tag)
and ArupRS , yes, I will explain B v D in this post and the other issues in a different post.

Above are the full sentences with each option inserted.

Both whereas and although are conjunctions that show contrast, but they are slightly different.**
Although means in spite of the fact that.
Whereas means compared with the fact that.

• Although suggests that the contrast is unexpected, counterintuitive, or surprising.
Although he hated war, he became a brilliant five-star general.

• Whereas does not usually suggest surprise—just contrast.
Whereas newer airplanes have a USB slot for each seat, older airplanes have no USB slots placed anywhere.

• The sentence in this question contains contrast that is not surprising
Europe does X to ensure Y. The U.S. does not do X and does not ensure Y.
-- Whereas in Europe regulators do X to ensure Y, in the U.S., no attempt is made to do X, as is clear from NOT Y.
-- It is no surprise that European countries are more conscientious about keeping the economic playing field fair than the U.S. is.

Option B is better than option D because the sentence merely highlights what Europe does in a certain context and what the U.S. does not do in that context—whereas is the better word to use when describing a contrast that is not surprising.

Hope that helps.


** -- WHEREAS: Oxford Dictionary online proxy, here and Oxford Learners Dictionary online, here ("used to compare or contrast two facts")
-- ALTHOUGH: Oxford Learners online dictionary, here ("used for introducing a statement that makes the main statement in a sentence seem surprising")

Subtle, but beautiful. Thanks!

Posted from my mobile device

Our dear generis explained it perfectly.

In general, for every question that makes a comparison we have to be very focused on the things that are being compared.

E.g. Person to Person, Action to Action, Place to Place.
The GMAT will often trick us into comparing Place to Action, Person to Place etc.

Country to Country: Unlike the country of Norway with its fridgid temperatures, Madagascar has quite mild winters.
Country to Occurence: Unlike the country of Norway, winters in Madagascar tend to be very mild.


If we are able to get the comparison right, there are often only 1-2 possible answer choices left.

**I address the difference between B and D more thoroughly in this post, here
I address (C) more thoroughly here

THE PROMPT

Unlike regulators in Europe who aim to prevent airlines from building monopoly positions at European airports, in America there are no such endeavors, as evidenced by the fact that at 40 of America’s 100 biggest airports, a single airline accounts for more than half the capacity of the airport. 

THE ANSWER CHOICES


• Unlike in a comparison must compare two nouns that are parallel
• in America is a prepositional phrase, not a noun
• Wrong comparison: regulators are compared to in America
• The who in this option is not problematic because the preposition unlike needs to be followed only by a noun, not by a clause (compare to C)


• Whereas is a conjunction that usually does no more than contrast two things—in other words, whereas does not suggest that the contrast is surprising.
• This sentence contrasts what Europe and America do in situation ABC. What each does is simply different and not surprisingly so. (Compare to although in option D)
• the two items compared are parallel: in Europe and in America.


• Wrong comparison: European regulators are compared to in America
• The who leaves a fragment.
Whereas is a subordinating conjunction that must be followed by a clause containing a subject and a verb
Whereas European regulators who do X, in America there are no such endeavors as X
-- that red part is not a clause with a subject and a verb.
No verb exists for European regulators. The who-clause "eats" the only verb.


• Although is slightly different from whereas.
-- Although suggests that the contrast is surprising.
-- Whereas merely highlights a contrast without suggesting surprise.
-- In Europe, efforts are made to prevent airplane monopoly positions. In America, no such efforts are made.
That difference is not inherently a surprise. Whereas is better than although.


• Even though is a slightly less formal version of although.
Same problem as that in D. (Even though suggests contrast that is surprising. The sentence suggests just difference, not surprising difference.)
• Wrong comparison: European regulators are compared to in America

******

In options A, C, and E, we first hear about regulators or European regulators.
Strip this sentence to figure out what the heck is being compared.

Unlike regulators in Europe who [try to stop problem XYZ] aim to prevent airlines from building monopoly positions at European airports, in America there are no such endeavors [attempts to stop problem XYZ], as evidenced by the fact that at 40 of America’s 100 biggest airports, a single airline accounts for more than half the capacity of the airport. 

The sentence, stripped:
Unlike regulators in Europe who try to stop problem XYZ, in America there are no attempts to stop problem XYZ.

Unlike X, Y
As Arro44 notes, in a comparison, X and Y must be the same kind of thing.
A regulator is a person.
in America is a prepositional phrase (PREPOSITION + place)
In A, C, and E, the introductory phrases lead with a noun
X = people
Y = IN a place

Right after the X element ends with a comma, we have the Y element
That Y element, in America, is in the non-underlined portion, and thus we are locked into that second structure.

The comparison must be between (what happens) in America and in Europe

abhisheksemwal and Shashwatp , I hope that analysis helps.
If it does not, be specific about what is still confusing and tag me. I will be happy to try to help.

elifceylan , I wonder whether a post got deleted?

I cannot see any posts indicating that one problem with C is who, though you are correct.

In addition to comparing unlike things (European regulators and in America),
option C lacks a full clause after whereas.

Whereas European regulators who aim to prevent airlines from building monopoly positions at European airports,
in America there are no such endeavors,

The first part of the sentence is not a clause and it should be.
Whereas is a subordinate conjunction that must be followed by a clause with a subject and its own verb that is also a complete thought.
-- The subject of the who-clause is WHO. (The who-clause is its own clause. It needs its own subject, which is WHO, and WHO needs its own verb.)
-- The verb of the who-clause is AIM TO PREVENT
No verb exists for regulators.
Remove whereas. We should have a full clause.

No whereas:
European regulators who aim to prevent XYZ.
Those words are not a complete thought. No verb exists for the subject regulators.

European regulators [who aim to prevent XYZ].
The regulators WHAT? Do what? Or are what?

Same idea, but this version is correct because it does not have a who that "eats up" the one verb callable:
Correct: Whereas one boy studied diligently, his brother never studied.
Now watch when I add a "who":
Wrong: Whereas one boy WHO studied diligently, his brother never studied.

Remove whereas. Whatever follows whereas must be an independent clause that expresses a complete thought and can stand on its own.

No whereas, wrong:
One boy WHO studied diligently.
Not a complete thought.
One boy [who studied diligently] ... WHAT? Did what?

Option C could say something such as

Whereas European regulators who attempt to prevent airline monopolization exert a lot of effort, American regulators of monopolization do nothing."
In that case, the verb for regulators would be exert

Wrong: The man who hollered all night.
(The sentence is not a complete thought and cannot stand on its own. Add commas to see the problem more easily.
The man, who hollered all night, ____. What? Did what?)

Correct : The man hollered all night. (no relative pronoun who that uses up the verb.

Correct: The man who hollered all night kept me awake.
(Two verbs, one for each subject, man and who.)

One more. Relative pronoun THAT rather than WHO, same concept.
Wrong: The dog THAT barked.
Correct : The dog barked.
Correct : The dog that barked seemed angry.

Option C is ungrammatical because whereas is not followed by an independent clause that can stand on its own.

I hope that helps.

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