GMAT Critical Reasoning (CR) | There is clear evidence that the mandated use of safety seat

There is clear evidence that the mandated use of safety seats by children under age four has resulted in fewer child fatalities over the the past five years. Compared to the five-year period prior to the passage of laws requiring the use of safety seats, fatalities of children under age four have decreased by 30 percent.

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

(A) The number of serious automobile accidents involving ...........children under age
...

---