E is right.

Your topic subject line also gave away the clue

Not only did the topic line give a clue,but OA posted also gives the answer. I have read somewhere that "nor" should be preceded by "neither".But in this case,"neither" is not used.My question is when is this usage(of nor without neither) applicable.

The sentence can be constructed as Neither X nor Y happened . Other way is X didnt happen nor did Y. If X and Y are concise I guess you can use the first structure, else for bigger clauses the second structure is simpler.

e.g.

Lewis and Clark were not the first white men to cross the continent from the Atlantic to the Pacific north of Mexico, nor did they visit places not already seen and mapped by generations of native people.

Neither were Lewis and Clark the first white men to cross the continent from the Atlantic to the Pacific north of Mexico, nor did they visit places not already seen and mapped by generations of native people.

karanrulz4ever wrote:Not only did the topic line give a clue,but OA posted also gives the answer. I have read somewhere that "nor" should be preceded by "neither".But in this case,"neither" is not used.My question is when is this usage(of nor without neither) applicable.

Nor can be used alone:

IN that case the structure of the sentence will be:

Negative sentence + Nor + Reversed Subject Verb Sentence

Examples:
Yet the Deepwater Horizon blowout is not unprecedented, nor is it yet among the worst oil accidents in history.

in D, had has been unnecessarily used. In this case the tense should be kept same.

Answer is E.