This took me 1:03.
There may be a number of ways to solve this but the best way might simply be to predict the answer. A flickering view of the question stem indicates that a FLAW is being looked for. Keeping that in mind, you read about a noisy factory, two sets of people (new workers and old) and an issue regarding ear plugs. I daresay it is common knowledge that loud noise can cause hearing loss and frankly that is what I was looking for in the answer choices.
Let's go through them one by one in any event to see if we could knock them out anyway.
(A) Because the noise in Ace's factory is absorbed by soundproof walls, it cannot be heard by Ace executives in their offices.
Well, this isn't a flaw in the decision about ear plugs. It is irrelevant.
(B) Many of the new employees interviewed said they would not wear earplugs on the job
The decision was not to have them wear earplugs in the first place, so how does this affect the issue either way? Out.
(C) Issuing earplugs to all new employees would be a less effective method of reducing employees' exposure to noise than altering the machinery to be less noisy would be.
Ok, so there is a better way of solving the problem. A better way doesn't mean another way has a flaw. Out.
(D) The experienced employees' lack of discomfort is attributable to hearing loss caused by the factory noise.
Bingo.
(E) The machines in Ace's factory have not become any noisier since the experienced workers were originally hired.
But they are still just as noisy, right? So...we still have a problem, right? Regardless, how is this a flaw?