Lsat-13-1-19

19.   The use of automobile safety seats by children aged 4 and under has nearly doubled in the past 8 years. It is clear that this increase has prevented child fatalities that otherwise would have occurred, because although the number of children aged 4 and under who were killed while riding in cars involved in accidents rose 10 percent over the past 8 years, the total number of serious automobile accidents rose by 20 percent during that period.

Which one of the following, if true, most strengthens the argument?

(A) Some of the automobile safety seats purchased for children under 4 continue to be used after the child reaches the age of 5.

(B) The proportion of serious automobile accidents involving child passengers has remained constant over the past 8 years.

(C) Children are taking more trips in cars today than they were 8 years ago, but the average total time they spend in cars has remained constant.

(D) The sharpest increase in the use of automobile safety seats over the past 8 years has been for children over the age of 2.

(E) The number of fatalities among adults involved in automobile accidents rose by 10 percent over the past 8 years.

the answer is B. why B?I think B should  weaken  the conclusion.

Thanks

B是说，涉及孩子的车祸的比率（the proportion）没变。这样的话，由于车祸总数上升20%，那麽，涉及孩子的车祸的总数也应该上升20%。