Unlike traditional retailers that deploy one new product line per seas

"unlike traditional retailers" who? the subject must follow the comma, out C and A.
Then we can eliminate B because the form COMMA + ING modifies the preceding clause, and in this contest is wrong. This kind of modifier expresses the consequences of the previous verb ( for example), as you see this is not the case.
We are down to D and E. In E "have been able" must be parallel with the next verb, but this option uses "stayed": not parallel.
D "have been able to (...) and stay" correct
D is the answer

Let me know if it s clear

Looking for logic, a little beyond just structure and grammar, might reveal new dimensions to this question. – What does - Unlike, - a transition comparison marker try to contrast? It is contrasting the traditional retailers that deploy one new product line per season with fast fashion clothiers, who deliver new looks every week. The action by both the set of peoples is what is sought to be projected. That the latter is able to respond to media and demand fluctuation is corollary to the event of delivery of new looks every week; Thus, I feel, B projects the comparison better than D, which relegates the all important weekly delivery as a modifying post, rather than as the main focus. I concede D as the OA, but mine is just another angle.

Hi Zarrolou,
This part is still not clear to me and others, could you please elaborate this rule with some example or in a more simple manner ?

thanks

- - Stayed incorrectly brings in Past tense

I wish to impart my perception regarding the confusion that seems to be there. The role of the adverbial modifier is as follows.1. If placed in the middle of the sentence separated by a comma, then this present participle modifier modifies the entire preceding clause or the gist or the result or the preceding clause. When I say preceding clause, prepositional phrases offset by a comma are not essential ones and therefore can be even dispensed with; the remaining structure will still make sense and stand alone. That is the reason that in the given choice B, the consideration of the traditional clothiers is unnecessary and should be ignored for the sake of identifying the true preceding clause. Logically, taking the traditional retailers to be able to respond to fluctuations in demands and media events does not go with the intended meaning of the text, which by Paradox wants to say that the fashion day clothiers are one up above the traditional people. Therefore, we can see that the pronoun ‘them’ logically leans on the fashion dealers rather than on the traditions dealers.
Let me stress, that the true focus of the text is to compare deployment for a full season with deployment (delivery) every few weeks.
Beyond this much pondering, I feel that the ball is in VERITAS’s court.

Main error in B and E is : respond to fluctuations in demand and media events (meaning error)

whats does fluctuations is media events mean?

respond to media and fluctuations in demand is correct.

Option B suggests, as a general rule, fast fashion clothing retailers always stay ahead of traditional retailers, as evident from the second independent clause starting with verb 'stay', whereas option D rightly points out 'delivering new looks every few weeks' as the reason for fast fashion clothing retailers staying ahead of traditional retailers.

Following aspects decide the above problem:

1. Modifier – “unlike traditional retailers…” must modify something like retailers.
Choices A and C do not do so, so they are incorrect.

2. choice B: modifier “enabling them” makes it look like retailers are enabling looks or themselves and this does not make sense.

3. Also in choice B, after the first verb, the sentence is “Retailers deliver new looks and stay ahead…”. This isn’t the logical meaning – it treats those two as separate-but-equal events, when in actuality the delivering is what allows them to stay ahead.

So B is incorrect for aspects 2 and 3.

4. fluctuations in demand and media events seems to indicate fluctuations in demand and fluctuations in media events which does not make sense.
option D corrects this error as response to media events and fluctuations in demand.

just my 2 cents on why I prefer D to B:
the original sentence sets the tone!!! It clearly mentions that by delivering - they have been able to do so!
B, on the other hand, makes everything as a general rule. If X happens, Y happens for sure. No, by doing X, they have reached to Y.
Present perfect plays an important role here, as it gives the time frame that something started some time ago in the past, and still continues.

Verb -ING modifier preceded by comma - Either present additional information about the preceding clause or present the result of the preceding clause.

Here "Enabling them" correctly modifies the preceding clause. Here the Verb -ING modifier is presenting the result.

Fast Fashion Clothing deliver new looks every week and this action enabled them to respond to the fluctuating situations.

This is also correct "Respond to fluctuations in demand and media events"

Responding to [ Fluctuations in Demand and media events]

Fast fashion responded to the media. Fast fashion responded to the fluctuating demands. So respond to is common for both. Hence this is also correct.

The only problem we are having here is in the tenses.
Usage of presentence here mean - Fast Fashion retailer is going to deliver new look every few weeks forever.
While option "D" Correctly says that the event started sometime back and it continues.

Presentense - Sun Rises in the east - Fact or universal truth. Usage of presentence is correct.
Sheela studies for her exam - Here it means, whenever there is an exam for her she will study. Again this is a fact.

But here we cant say that Fast Fashion is going to deliver new look every few weeks forever.
Instead we can understand, that this event has started sometime back and it continues. Hence usage of present perfect is fine here.

If option D is not there definitely we can go for B bcos SC is all about choosing the best choice among 5 options.

OFFICIAL EXPLANATION

The clearest Decision Point here is the Modifier — "unlike traditional retailers..." must modify something that could be like traditional retailers. Choices A and C do not do so, so they are incorrect. The decision between B,D, and E is a bit more nuanced. But look at the logic of choice B: by putting modifier ”enabling...” after the first verb, it creates the sentence "Retailers deliver new looks and stay ahead...”. This isn’t the logical meaning — it treats those two as separate-but—equal events, when in actuality the delivering is what allows them to stay ahead. Choice D fixes this, using the "and” conjunction to treat the other two, more-related verbs as the equal events. ”...have been able to respond to fluctuations in demand and stay ahead..." is the logical meaning, making D correct.

d and media events, and stay ---deliver and stay should not be parallel. Stay ahead of the competition is the result of delivery.

'Stay' may not be a parallel action to deliver as has been made out. IMO, it is a parallel action to respond in the modifier part. We should parse B as ----fast fashion clothing retailers deliver new looks every few weeks, enabling them (to respond to fluctuations in demand and media events, and(to) stay ahead). The question is not one of verb parallelism but of infinitive parallelism within the modifier.

Only one reason that D is a tad better than B is that of a better word - order. Let's consider the modifier. D says that the fast fashion clothing retailers … have been able to respond to media events and fluctuations in demand and stay ahead. This correctly means that the fluctuations pertain only to the demand and not to media events.
On the contrary, B says --- fast fashion clothing retailers …. To respond to fluctuations in demand and media events. This might mean that both the demand and media events undergo fluctuations. This is not logical.

Unlike traditional retailers that deploy one new product line per season, delivering new looks every few weeks has enabled fast fashion clothing retailers to respond to fluctuations in demand and media events and stay ahead of the competition.

The phrase "Unlike traditional retailers that deploy one new" should modify "fast fashion clothing retailers" and hence, "fast fashion clothing retailers" should be followed by the phrase "Unlike traditional retailers that deploy one new". When we quickly glance at the options, we can eliminate options A and C in which "fast fashion clothing retailers" is not followed by the modifier phrase.

A. delivering new looks every few weeks has enabled fast fashion clothing retailers to respond to fluctuations in demand and media events and stay - Out as per above
C. the delivering of new looks every few weeks has enabled fast fashion clothing retailers to respond to fluctuations in demand and media events, staying - Out as per above

Now let's look at E

E. fast fashion clothing retailers, by delivering new looks every few weeks, have been able to respond to fluctuations in demand and media events and stayed

- In E the usage of "stayed" is incorrect

B. fast fashion clothing retailers deliver new looks every few weeks, enabling them to respond to fluctuations in demand and media events, and stay

D. fast fashion clothing retailers, by delivering new looks every few weeks, have been able to respond to media events and fluctuations in demand and stay

With B there is a problem with the modifier "enabling". it creates the sentence “Retailers deliver new looks and stay ahead…”. This isn’t the logical meaning – it treats those two as separate-but-equal events when in actuality the delivering is what allows them to stay ahead.

Hence, Answer is D

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I eliminated D in my first pass because "able to respond to media events and fluctuations in demand and stay"

Isn't it a grammar error to use A and B and C, without a comma? Shouldn't it be A and B, and C? (which was B)

Nice shortcut. I see the approach is staight to the point . Probablyy a bit more clear would help us

A and C are incorrect because they both incorrectly compare "traditional retailers" to delivery...
B and E are incorrect because they state "respond to fluctuations in media events.." which doesn't make sense
B - also in B the wrong meaning is conveyed. The response IS THE DELIVERY, so delivering new looks doesn't enable them to respond...it is the response
D is Correct

Dear DmitryFarber VeritasPrepBrian AnthonyRitz IanStewart GMATGuruNY,

Why is choice B. wrong?

I don't see the problem described in the solution above. I think "respond" and "stay" - both of which are within V-ing modifier - are completely parallel here.
Please see the breakdown of the structure according to choice B. below:

fast fashion clothing retailers deliver new looks every few weeks, enabling them to
respond to fluctuations in demand and media events,
and
stay