Modifier problem

[nipunranjan]

The growth of the railroads led to the abolition of local times, which was determined by when the sun reached the observer's meridian and differing from city to city, and to the establishment of regional times.

(A) which was determined by when the sun reached the observer's meridian and differing
(B) which was determined by when the sun reached the observer's meridian and which differed
(C) which were determined by when the sun reached the observer's meridian and differing
(D) determined by when the sun reached the observer's meridian and differed
(E) determined by when the sun reached the observer's meridian and differing

[Mike@Magoosh]

The growth of the railroads led to the abolition of local times, which was determined by when the sun reached the observer's meridian and differing from city to city, and to the establishment of regional times.

(A) which was determined by when the sun reached the observer's meridian and differing
(B) which was determined by when the sun reached the observer's meridian and which differed
(C) which were determined by when the sun reached the observer's meridian and differing
(D) determined by when the sun reached the observer's meridian and differed
(E) determined by when the sun reached the observer's meridian and differing

I'm happy to help with this.

I would say that the primary issue here is not so much modifiers as parallelism. First of all, here's a blog about modifiers:
https://magoosh.com/gmat/2013/modifiers- ... orrection/
Here's a blog on participial phrases (used in the OA):
https://magoosh.com/gmat/2012/participle ... -the-gmat/
Here's a blog on parallelism:
https://magoosh.com/gmat/2013/parallelis ... orrection/

So, let's look at the parallelism in the answer choices:

(A) which was determined ... and differing --- full verb//participle = WRONG
(B) which was determined ... and which differed --- full verb//full verb - correct parallelism
(C) which were determined ... and differing --- full verb//participle = WRONG
(D) determined ... and differed --- participle//full verb = WRONG
(E) determined ... and differing --- participle//participle = correct parallelism

Only choice (B) & (E) have correct parallel structure. Choice (B) has a subject-verb agreement problem, and even if that were correct, the double-"which" construction is awkward. BTW, see this blog on S-V Agreement:
https://magoosh.com/gmat/2013/subject-ve ... orrection/

This leaves (E) as the only answer that is totally free of grammatical mistakes. OA = (E)

Does all this make sense?
Mike

[vietmoi999]

C can be still considered paralel.

which are
determined
and
differing

but to get this paralelism, "which were" must run a long way to go to "differing" and this paralelism is not prefered, compared with the clear paralelism in choice E.

we should learn the new things from og and gmatprep questions, which is not explained fully

[faraz_jeddah]

The growth of the railroads led to the abolition of local times, which was determined by when the sun reached the observer's meridian and differing from city to city, and to the establishment of regional times.

(A) which was determined by when the sun reached the observer's meridian and differing
(B) which was determined by when the sun reached the observer's meridian and which differed
(C) which were determined by when the sun reached the observer's meridian and differing
(D) determined by when the sun reached the observer's meridian and differed
(E) determined by when the sun reached the observer's meridian and differing

This is an usual question. What is the source?

Why is D Wrong? How are reached and differed not parallel?

[GMATGuruNY]

The growth of the railroads led to the abolition of local times, which was determined by when the sun reached the observer's meridian and differing from city to city, and to the establishment of regional times.

(A) which was determined by when the sun reached the observer's meridian and differing
(B) which was determined by when the sun reached the observer's meridian and which differed
(C) which were determined by when the sun reached the observer's meridian and differing
(D) determined by when the sun reached the observer's meridian and differed
(E) determined by when the sun reached the observer's meridian and differing

In A and B, which WAS (singular) seems to refer to abolition (the nearest preceding singular noun), implying that the ABOLITION was determined by when the sun reached the observer's meridian.
Not the intended meaning.
Eliminate A and B.

A conjunction such as and must connect PARALLEL FORMS.
In C, were determined (verb) and differing (adjective) are not parallel.
In D, determined (adjective) and differed (verb) are not parallel.
Please note that differed can serve only as a verb; it cannot serve as an adjective.
Eliminate C and D.

The correct answer is E.

Why is D Wrong? How are reached and differed not parallel?

If differed is parallel with reached, then both verbs must have the same subject: the SUN.
The result is the following:
The SUN DIFFERED from city to city.
Not the intended meaning.

I believe that this is an official SC from GMAT Prep.