Automobile Dealer' s Advertisement: The Highway Traffic Safety Institute reports that the PZ 1000 has the fewest injuries per accident of any car in its class. This shows that the PZ 1000 is one of the safest cars available today. Which of the following, if true, most seriously weakens the argument in the advertisement? ["In recent years many more PZ 1000's have been sold than have any other kind of car in its class.", 'Cars in the class to which the PZ 1000 belongs are more likely to be involved in accidents than are other types of cars.', 'The Highway Traffic Safety Institute issues reports only once a year', 'The difference between the number of injuries per accident for the PZ 1000 and that for other cars in its class is quite pronounced.']