(A) Incorrect . For the reason mentioned above.
(B) Incorrect . For the following reasons:
- Repeats the meaning and idiomatic error of the original sentence.
- ?for?, a preposition, is followed by a clause "many of the planes were_". A preposition can never be followed by a clause.
(C) Incorrect . For the following reasons:
- ?where? refers to a place, not ?time?. Therefore, its use is incorrect.
- The use of demonstrative pronoun ?these? without a noun following it is not recommended. The demonstrative pronouns ?this? and ?these? need to be followed by a noun e.g. this idea, these records etc.
(D) Incorrect . For the following reasons:
- The structure ?so new such that? is incorrect. It should be ?so new that_".
- Given the context of the sentence, the correct word for ?time? is ?when?, not ?in which?. (OG explanation says so and I agree)
(E) Correct . ?earned? acts as a verb-ed modifier correctly modifying ?records?. Everything is fine with this option.