What is the source of this question? I will be very surprised if it is an official GMAC question, because choice A is wrong, and it is not quite clear whether choice D is correct. (If it is a

Kaplan question, please tell me ASAP. I work for

Kaplan, and we don't like to leave errors lying around in our materials.)

The fact that left-handed people have an advantage in painting simply does not prove that a larger proportion of left-handed people actually BECOME PAINTERS (choice A). An inference question does require an inevitable inference, and this one is not.

D may be inevitable, depending on how we interpret the statement that left handers contract viruses "more frequently" than right handers. If it means that ALL left handed people contract viruses more frequently than ALL right handed people, then D is clearly inevitable: Every left handed person, whether a painter or not, must be more susceptible than every right handed person. Therefore, left handed painters (just because they ARE left handed, not because they are painters) must be more susceptible than "the general population", which contains both righties and lefties.

If that is the intended meaning of "more frequently", then D could even say "all", not just "most". If "all" is inevitable, then "most" is inevitable as well, and so D is still correct.

But if "more frequently" is a statistical statement -- i.e., left handers are more susceptible ON AVERAGE, but the distributions of susceptibility may overlap -- then we cannot even conclude "most". We can't even conclude "any". Not only do we not know whether there are more righties than lefties in the overall population (as others have noted); we do not know where the left-handers who are painters may sit within the overall "susceptibility" distribution of left-handers. If they all happen to be at the low end of that distribution, they COULD be less susceptible than the overall population, which is made up of all the right handers and all the left handers including the most susceptible ones.

I think that we are supposed to interpret "more frequently" as an absolute statement, not statistical, even though we know that it would be statistical in the real world. Given that interpretation, D is inevitable, and so is the correct answer.

No, the source of this question is Bellcurves.com