The average age and racing experience of the drivers at the Indianapolis 500 automobile race increased each year between 1965 and 1980. The reason for the increase is that high-speed racing drivers were living longer than their predecessors. Race-car safety features that reduced the severity of crashes of the kind that took drivers' lives were primarily responsible for the increase in the average age of the Indianapolis 500 competitors.Which of the following, if true, would be most likely to be part of the evidence used to show that safety measures on the cars that protected drivers in major crushes were responsible for the increase in the average age of drivers at Indianapolis race?
（A）Younger drivers at high-speed were involved in major accidents at a slightly higher rate than were old drivers between 1965 and 1980.
（B）Major accidents on high-speed race tracks occurred at about the same frequency in the year after 1965 as in the year before 1965.
（C）The average age of drivers attempting to qualify for the Indianapolis 500 decreased slightly between 1965 and 1980.
（D）Accidents on highways in the United States occurred at about the same frequency in the year after 1965 as in the year before 1965.
（E）Other safety features, involving the condition of the racetrack and the uniforms worn by the drivers while driving, were adopted at Indianapolis between 1965 and 1980.
正确答案是B，其他四个是无关选项，但是看不出B对在哪里，请高手指点！作者: bull11389 时间: 2012-9-8 14:34
B) is a necessary assumption for the question.
If death rate is down, it could be that the safety features were better or the number of accidents were LOWER.作者: starry1008 时间: 2012-9-9 07:53
