Confused when to use 'which ' pronoun

[DO-OR-DIE]

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


What cud be the correct answer . And moreover I am confused when to use which deliberately .. because in the above sentence I feel which is necessary but I am confused ..


Thanks
Senthil

[RonPurewal]

hi - if you're going to post questions in this folder, you must post the source for each one; otherwise, we'll have to delete the threads. (see the sticky for the appropriate rules, and for the list of banned sources.)
thanks.

by the way, please spell out words such as 'could'; abbreviations such as 'cud' make posts harder to read. thanks.