Answer choice (A)

While reading the answer choices I eliminated (A) because I thought it was a mistaken negation. I thought the premise and conclusion was that Premise: (Because) prevented variety of readily available books Conclusion: detriment book consumers ~VRAB -> ~Better off (=detriment) On the other hand (A) states If greater variety of readily available books -> Book consumers better off VRAB -> Better off Isn't this a mistaken negation? It would be really nice if someone could provide an explanation. Thanks in advance!!