praveen, please explain your answer
I should really wait for OA, I may be jumping too early... anyway, here is my thought
first of all, I think there is a typo in A, choice A should exclude than in other words A should read "they originally seemed"
original sentence calls for more time to deteriorate than _ZZZ___
here we need a noun/pronoun to quantify (ZZZ) what is being compared. Only choices C,D & E provide that.
choice C is verbose
D is incomplete
only E makes correct comparison, also verb would highlight the uncertainty required in the comparison.
it originally seemed they would