The second sentence( "In a hospital study, however, subjects questioned immediately after they consumed alcohol underestimated the time necessary to regain their driving ability") ... makes the question tough to understand.

I don't take this as a tough question as posted by some of our friends. This is a typical weakening question in some other form because it included statistics and research. we can attack simply by pointing the flaw in type of data taken. Here if we can say that the observation was not unbiased we ca...