I need help from Stacey, with this one. I have been to couple of different site to get an answer for this one, but have had a fruitless pursuit. Thanks

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

A. which was determined by when the sun reached the observers meridian and differing

B. which was determined by when the sun reached the observers meridian and which differed

C. which were determined by when the sun reached the observers meridian and differing

D. determined by when the sun reached the observers meridian and differed

E. determined by when the sun reached the observers meridian and differing

Is the answer(D)?

Ali,

As is the case with many sentence correction problems, this problem contains several grammatical issues, including modifiers, subject-verb agreement, parallel construction, and clarity of meaning.

Let's first consider the subject-verb agreement issues. As "which" refers to "times," the noun directly preceding the comma, a plural verb is necessary. Since choices A and B include the singular verb "was," both can be eliminated.

Next, let's address the very tricky parallel structure in this sentence. The original sentence is attempting to state that local times were determined by one factor and that they differed from city to city. Thus, the logical assumption is that answer choice D - which uses determined and differed - is correct. However, by removing the subject they, answer choice D is equating determined , in which times is an object (the times were determined by something else), with differed, in which times is a subject (the times differed from city to city). Since this is a provable error in parallel construction, eliminate D.

Finally, the only difference between choices C and E is that C includes which were. By including which were, choice C implies that the "which were" refers to both determined and differing. In other words, choice C is actually saying which were determined by when the sun reached the observers meridian and which were differing from city to city. In this case, determined is not parallel to differing as the two serve different functions - the correct forms would be which were determined by when the sun reached the observers meridian and which differedfrom city to city - so answer choice C can be eliminated.

The credited answer is E, which correctly equates the past participle determined with the present participle differing.

Final thoughts: This is definitely a 700+ sentence correction problem, and possibly a 750+ problem. If you are still having difficulty with this one, feel free to ask further questions, but don't get hung up on it or let it stress you out. You will only see a similar problem on your actual GMAT if your verbal score is above the 95th (and perhaps 99th) percentile or if you are unlucky with your experimental questions. If one does appear as an experimental, simply eliminate the answer choices that cannot be correct (A and B), make a strategic guess, and move on. The worst decision with a problem of this type is to spend 5 minutes agonizing over the remaining answer choices. Be proactive (just like Jessica Simpson), and go!

Hope that helps.
-dan