Answer: A. The new law
Explanation: Considering that the goal of every traffic law is to reduce the number of deaths, and in this connection to constantly improve or pass a new law. It means not improving statistics and how easy it is to count the dead or how many high-profile traffic accidents there are, but to reduce the number of dead. Of course statistics are important in assessing the effectiveness of the law, but not the ultimate goal. So an experimental stimulus would be a new law.
On the other hand, statistics are always used in estimating and emphasizing the increase in traffic accidents, but often this is not a stimulus that affects people's awareness, and does not contribute to reducing traffic accidents, so it can be said that it is not always a stimulus.