GMAT Critical Reasoning (CR) | Re: While is true that effects of disease have been overlooked

So question A is incorrect because of appreciably, rite? I see the reasoning in A quite resembles that of many other correct options (C-->E, no C --> no E), but the word appreciably, as many point out, can break the argument, giving the possibility that Efffect (population declines) still happens while Cause does not, just not to the appreciable extent. So it may slightly weaken the argument (no C--> E still).

But Is this from GMATPrep? Can anybody confirm? If it is really from GMATPrep,