As is supported by evidence recently presented in mathematical symposi

I answered it in a haste as (B)......I guess the sentence in simple words is trying to say:

More and more unsolved problems are now being solved>>which is almost double the number of problems which could not be solved in 1950 and confounded=confused/tricked the then mathematicians'........

a) Twice as many as (the unsolved problems) that confounded----we dont need to write the ones in bracket, as the reference is quite clear, as the clause immediately after the comma is referring to the "unsolved problems" which is just before the comma.

b) double the number of problems --- this part looks like directly referring to the unsolved problems, giving it a meaning as if the number of unsolved problems were exactly the same number of overall problems that confounded (confused/tricked) mathematicians' of 1950- (irrespective of they were finally solved/unsolved).

c) same error as b

d) Twice as many as the problems that confounded.......here again the reference to unsolved problems is wrongly made to the whole set of problems which confounded 1950 Mathematicians', some of which would have been solved too........

e) same error as b

So A, is non wordy, correct reference, meaning contained and apt.

Experts: Pls correct my understanding